key: cord-0041367-p5dhqtov
authors: nan
title: ABSTRACTS OF PAPERS
date: 1968-07-01
journal: Am J Bot
DOI: 10.1002/j.1537-2197.1968.tb07429.x
sha: e808c29b36fd39202f2788852d26b22d21062d9f
doc_id: 41367
cord_uid: p5dhqtov

nan

7:00 7:00 8:30 9:00 9:00 9:00 9:00 9:00

General Section: breakfast and business meeting Mycological Society of America: breakfast Co-sponsored by Microbiological Section Developmental Section: contributed papers Paleobotanical Section: contributed papers Physiological and Developmental Sections: symposium Systematic Section: contributed papers Teaching Section: contributed papers CUEBS: special session P.M. 1:00 Physiological Section: contributed papers 1: 30 Developmental Section: contributed papers Joint meeting with General Section 1 :30 Systematic Section: contributed papers and business meeting 1: 30 Microbiological Section: symposium 2:00 General Section: contributed papers 2:00 Teaching Section: symposium 6:30 Annual Banquet, Botanical Society of America -The structure and development of the akinete of a blue-green alga, Cylindroepermum sp., was investigated with the light and electron microscopes. Only the sub-terminal cell which appears to divide immediately before the onset of development becomes an akinete. There is first an elongation and then a rounding out of the sub-terminal cell. The akinete that develops is larger than a vegetative cell, but it has the same cell-wall components and the same kinds of inclusions. An unusually large number of structured granules and ribosomes is present. Unlike the vegetative cell a heavy fibrous coat is laid down outside the inner investment and an electron-dense material, possibly pigment-containing, accumulates within the fibrous coat. The fibrous coat is of medium electron density and the pigment-containing material is drawn outward into rays as the akinete matures. The fibrous coat and the inner investment are separated bv a lucent space in the mature akinete. cells. This is demonstrated by phase-contrast and interference-contrast microscopy of living hyphae and by electron microscopy of preserved hyphae. The young hypha is divided into three protoplasmically differentiated zones: an apical zone, a subapical zone, and a zone of vacuolation. The apical zone extends from the tip basipetally 3-{j,.. and is characterized by an accumulation of cytoplasmic vesicles, often to the exclusion of other organelles. Vesicle membranes are occasionally continuous with plasma membrane. Ribosomes are notably infrequent in the apex, and endoplasmic reticulum is found only in the basal portion of this zone. The transition between the apical and subapical zones is gradual over a distance of several microns. Mitochondria are typically clustered in this transitional region. The subapical zone is largely non-vacuolate and contains representatives of all protoplasmic components including nuclei, dictyosomes, endoplasmic reticulum, abundant ribosomes, miorotubules, secretory__ vesicles, microbodies, and even a few lipid bodies. With increasing distance from the apex the subapical zone merges into the zone of vacuolation. The size and number of vacuoles increases progressively until the bulk of the protoplast is comprised of vacuoles. The demonstration illustrates hyphae of P. ultimum and compares the protoplasmic organization of this fungus with other fungal genera. These findings, along with observations on membrane differentiation and cytochemical reactions, support an hypothesis to explain the origin, transformation, transport and destiny of organelles involved in the expansion of cell surface at the hyphal apex. This demonstration presents models and drawings of the form of the fretwork among adjacent grana. The codirectionality of the helices leads to an integrated, interlocked fretwork. It is suggested that this complex system of intergranallamellae is derived, to a large degree, by fusions of membranes rather than by continuous growth of a once simpler system. DRYAND-The flower of Hibbertia scandens consists of five sepals, five petals many stamens (more than 100), and usually five carpeis. The sepal and petal primordia are initiated in acropetal (centripetal) succession. Mter the inception of the fifth petal, the flat floral apex increases considerably in Width. During this growth of the apex, the stamen primordia are formed in centrifugal sequence. The first stamen primordia arise in groups, usually alternately with the petal primordia. These groups of stamen primordia are formed almost simultaneously, either in continuity with the spiral phyllotaxis of the perianth, or proceeding from one side of the floral apex to the other. Then the inception of more stamen primordia lateral to and outside of the first ones closes the gaps between the initial staminal groups. This process, which occurs rapidly, makes it rather difficult to determine the number of the initial groups of stamens. It seems that in some buds five staminal groups are discernible, whereas in other buds more than five such groups have been distinguished. A special technique was used to obtain a three-dimensional picture of the developing floral apices and buds. The material was stained in alcoholic acid fuchsin and photographed completely immersed in 100% ethyl alcohol, using a microscope with an incident light condensor and objectives with dipping cones. As a result of this technique, the protoderm cells of the floral apex and the primordia of the appendages become visible. to be described had two objectives: (a) to determine if meristematic cells could be induced to enter a particular interphase period and caused to remain in this period for several hours, and (b) to determine if the level of metabolism was phasic in nature as a cell progressed through the mitotic cycle. A stationary phase in the root meristem of excised pea roots was established by prolonged carbohydrate deprivation in sterile culture medium. When established, cells that had collected in the G, period of the mitotic cycle were induced to enter S by pulses or spurts of sucrose provision. Progression and cycle location of the G, cells induced to enter S were measured with tritiated thymidine and radioautography. The results indicated that the number of G, cells induced to enter S increases directly with the spurt duration and that cells could be positioned and retained in the Sand/or G2 periods by varying the duration of the spurt. The data support the hypothesis that S and maybe M have a relatively larger dependence on carbohydrate availability and presumably a greater energy requirement than G, or G2• 1:45

Webster, P. L., and J. Van Roots of Pisum sativum have been cultured under nitrogen for different lengths of time to investigate the effects of anaerobic conditions on the mitotic cycle and to compare these effects with those of sucrose starvation. Stationary phase pea roots with meristem cells in either G, or G 2 have been exposed to H3-TdR in the presence and absence of both sucrose and nitrogen for periods of up to 12 hr. Liquid scintillation counting has shown that the onset of DNA synthesis requires both oxygen and a carbohydrate source. Radioautography further demonstrated that the entry of Gi cells into Sand G2 cells into mitosis is prevented under anaerobic conditions. This inhibition is completely reversible upon return to air, the patterns of entry of cells into S and mitosis being unaffected. The results of short air spurts on pushing cells through the cycle will also be described.

Van't Hof, J., and P. L. Webster. Brookhaven National Laboratory, Upton, N. Y.-ANAEROBIOSIS AND THE INITIATION OF CELL DIFFERENTIATION IN ROOT MERISTEM CELLs-During the course of experimentation designed to study variations in energy requirements in the mitotic cycle, it was discovered that prolonged anaerobiosis prevented initiation of chromosome replication and cell division of most but not all stationary phase G, and G2 cells. The present experiments were designed to localize and characterize the exceptional cells. This was accomplished with radioautography of squashed and sectioned material and scintillation counting. After establishment of the stationary phase by carbohydrate deprivation, excised Pisum root tips were provided sucrose ana cultured under N 3 for several hours. Scintillation counting showed tritiated thymidine was incorporated during anaerobiosis at a low but significant rate. Radioautographs of squash preparations indicated that incorporation occurred in a very small percentage of cells and radioautographs of sectioned material showed the labeled cells to be primarily the group that gives rise to the pericycle or cells closely associated with the pericycle. The results suggest that the metabolic machinery for or associated with differentiation may be present and operative soon after or even during the division of the meristematic initials.

2: 15 DeMaggio, A. E., and R. H. Wetmore. Dartmouth College, Hanover, N. H., and Harvard University, Cambridge, Mass. -POLYPLOIDY AND FERN MORPHO-GENESIS-The major objective of the work to be reported is to determine the extent to which increasing levels of nuclear DNA, brought about by experimentally induced increases in the genome, contribute to cytological and physiological differentiation in plants. Two polyploid series of fern plants have been utilized, a gametophyte series and a sporophyte series, both of which have been produced by cultural techniques and maintained aseptically. Routine cytological examination of plants in each series indicates that individuals at every level of ploidy are characterized by a marked stability in chromosome number and, therefore, levels of nuclear DNA are also considered to be stable. With this material we have examined various cytological phenomena and physiological processes in cells where the amount of nuclear DNA is known, constant, and can be increased by substituting cells at higher levels of ploidy. Measurements of respiratory and photosynthetic activity of plants in each series are interpreted to show the extent to which these processes are influenced by ploidy levels. has been shown to exist between nuclear volume, DNA content, and minimum mitotic cycle time in several diploid species of plants. Evidence indicates that the synthesis of nuclear DNA may be a critical factor in regulating the duration of the mitotic cycle. The implication is that a cell which has to replicate twice the amount of DNA as another cell will take twice as long to complete the replication ( Van't Hof and Sparrow, 1963) . In animal tissue culture studies a dependence of synthesis time on nuclear DNA content has been recorded. However, the metabolic status of the culture may significantly alter the synthesis and total cell cycle times (Malamud, 1967) . 'To determine if similar correlations hold in a polyploid series of fern gametophytes (In, 2n, 4n) and sporophytes (2n, 4n) , the incorporation of a pulse of tritiated, thymidine was followed radioauto-. graphically for 72 hr in plants from each of the ploidy groups. Plants of Todea barbara wereremoved from sterile solid cultures and transferred to liquid media 3 weeks previous to pulsing. Pulsing was accomplished aseptically by adding tritiated thymidine to the medium (0.5~c/ml, sp act 2.0 C/mM) for.3 hr, followed by successive washes with lOOX unlabeled medium to remove unincorporated, thymidine. Plants were prepared for histological analysis, stained with Feulgen reagent and coated with, NTB-3 liquid emulsion. Estimates of chromosome number were" recorded to verify the ploidy of the material and eliminate possible endopolyploidy, The pattern of labeled cells in mitosis in the meristern was examined to detect possible mitotis cycle time variations between different histological zones. The results of these studies will be. discussed with reference to ploidy, nuclear volume, meristematic zonation, and, minimum mitotic cycle time. [Vol. 55 Developmental Section-continued 2:4. 5 Sharp, W. R., and D. Davidson . Case Western Reserve University, Cleveland-PHYSIOLOGICAL COM-PARISONS OF NORMAL PITH CALLUS WITH COLCHICINE-INDUCED CALLUS OF CABBAGE GROWN IN vrrno-s-Calluses form readily at the nodes of cabbage plants 3 months after treatment of the primary shoot apex with colchicine (2% in lanolin paste). Calluses also appear o~decapitated plants. Using the Murashige and Skoog medium, calluses from colchicine-treated and from decapitated plants have been cultured in vitro. Callus tissue from the latter plants grows moderately well on Murashige and Skoog medium; callus from colchicine-treated plants, however, requires the addition of coconut milk (1.5%) or~,~-D (0..5 mg/liter). Studies have been made of the nutnt.ion, respiration, intermediary metabolism and structure .of the two types of callus. These will be compared and discussed.

3:1. 5 Ball, E. North Carolina State University, Raleigh-TIME-LAPSE OBSERVATIONS ON DEVELOPMENT OF PHRAGMOPLASTS IN INDIVIDUAL PLANT CALLUS CELLS-Regardless of whether the cell was slightly or greatly elongated, the division figure could be either in a mass of cytoplasm at the center or adhering to a lateral wall. In the first case a meshwork of cytoplasmic strands extended outward from all sides of the two nuclei and connected with the peripheral cytoplasm. The cell plate developed outwardly through this cytoplasmic meshwork, which became a layer of cytoplasm extending to the lateral wall. When the division figure originated along a lateral wall there was an extension of a massive layer of cytoplasm between the derivative nuclei across the cell. Immediately back of this advancing front of cytoplasm was the developing edge of the cell plate. In neither case was a phragmosome developed prior to formation of cell plate. There was no conspicuous marginal enlargement of the phragmoplast as it developed across a dividing cell. When the cell plate reached the lateral wall it developsd a narrow edge which grew into a dissolved ridge of the original wall. The~ew. cell wall was deposited completely around the derivative protoplasts, yielding two cells separated by intercellular substances. The original wall, broken at the juncture with the new lateral walls, was sloughed off.

Whitmoyer, R. E., and H. T. Homer, Jr. Iowa State University, Ames-A CYTOLOGICAL AND HISTO-CHEMICAL STUDY OF I,EAF NODULE DEVELOPMENT IN PSYCHOTRIA BACTERIOPHILA Val.-Two suggested roles for bacteria in leaf nodules of varions plants are nitrogen fixation and production of a growth regulator (or hormone), both of which are necessary for normal plant growth. Various histochemical and ancillary techniques have been carried out at the light-microscope level to determine the nodular growth and activity from inception to time of leaf abscission. All visible nodules in leaves of different ages were punched out using a hypodermic needle and syringe. These nodules were then formed into pellets according to age and sectioned so that variations in both nodule orientation and activity could be observed. The bacterial mass within the nodule exhibits a strong uniform RNA reaction in very young and actively growing leaves. At maximum leaf enlargement this reaction decreases rapidly from nodule center to periphery and is negative at the time of leaf abscission. Other techniques indicate that nodule activity in some ways parallels leaf g~'owth and development. Elaboration of these results wJ!1 be presented.

Kordan, H. A., and R. D. Preston. University of Leeds, Leeds, England-NucLEOLAR VACUOLES AS LIQUID CRYSTAU; IN PLANT CELLs-Homogeneous-appearing refractile regions of interphase nucleoli of plant cells (commonly referred to as vacuoles under bright-field and phase-contrast microscopy) show optical anisotropy under polarizing microscopy in a number of plant, genera (Zamia, Lilium, Citrus, Zea, Poncirus, and Pinu.5*) . The degree of double refraction increases with an increase in size of the nucleolar inclusions. In unstained squash preparations and paraffin sections and in st ained histological preparations the inclusions show a polarizutiou cross the shape of which varies with the shape of the inchl~ion (spherical, ovoid, cylindrical). Jn specially stained preparations the polarization cross is JlO longer evident and the inclusions manifest distinct bright and dark alternations when rotated between crossed polars, appearing to be optically active. The loss of the polarization cross in these stained preparations coupled with the bright and dark alternations during rotation between crossed polars indicate that the nucleolar inclusions are a two-component system consisting of a birefringent core surrounded by a birefringent envelope. The anisotropic properties of the nucleolar inclusions in stained and unstained preparations and their variability in size and shape indicate that they are liquid crystals, possibly of the cholesteric type. separately and in combination were investigated. Three hundred ppm BA proved toxic, and fatally so, except in the presence of 300 ppm GA. GA increased overall plant height, leaf area, leaf fresh weight and dry weight, chlorophyll and protein. The effect of GA on retarding leaf senes~ence is far less significant than the effect of BA. BA alone produced nonsignificant effects on overall plant height, but it increased significantly the leaf area. fresh weight and dry weight as well as the production of leaf chlorophyll and protein. The interaction between GA and BA, analyzed at the 5% level of probabilitv. produced significant, inorease III leaf area, fresh weight. and chlorophyll, and also significant retardation of leaf senescence. Their interaction had no significant effect on overall plant height, leaf dry weight, or leaf protein content. 4: 1. 5 Laetsch, W. M. University of California, Berkeley-SENEsCENCE IN TOBACCO LEAVES: RELATION OF THE LEVEL OF SENESCENCE TO BLEACHING AND PO-TENTIAl, FOR CELL DIVISION-It was previously found that 2-mm discs from mature tobacco leaves could be maintained in the dark on a sucrose and mineral medium for more than 3 months and that callus could be induced from such tissue. One part of the present study concerns the rate of chlorophyll loss in discs from very young leaves, partially green dark-grown leaves, and leaves in various stages of senescence. The other part concerns the potential of tissue which has senesced on the plant or in culture to proliferate. When discs from dark-grown leaves are placed in the light for 2 days, they have half the chlorophyll of discs from mature leaves. LIttle, If any, of this chlorophyll is lost when the discs are maintained in the dark for 2 weeks. Discs from mature leaves lose at least. .50% of their chlorophyll in the same time. Dis(;s from young leaves of light-grown plants also lose their chlorophyll in the dark much slower than older leaves. It app.ears that chlorophyll~urnover might ?e almost non-existent III young cells. DISCS from leaves III various stages of senescence were cultured in the dark on Murashige and Skoog medium. Discs from leaves with only 12% of their former chlorophyll content proliferated into 705 callus. Discs from the same series of senescent leaves were maintained in the dark for 3 weeks on sucrose and minerals and then placed on a complete medium. All these discs formed callus. When discs from mature leaves were bleached rapidly on agar in the dark and transferred to complete medium, they would not form callus if they had lost more than 60% of their chlorophyll. It is concluded that the senescence of intact tobacco leaves is largely a matter of limiting factors and that the initiation of irreversible degradative processes does not occur until the final stage of senescence. 'Templini' (variegated leaves) can be stimulated to subdivide. The cells so formed continue to divide producing first a mound of cells, and then, on leaves and stems, t.wo-stipulate leaves, and on peduncles, male flower primordia. The stimulus to division of epidermal cells is provided by injury to or partial removal of the root system. The number of outgrowths on a leaf blade may be as high as 4,000, on a petiole 500, on a stem internode in the thousands, and on a peduncle in the hundreds. None of the floral outgrowths produce fully developed flowers possibly because they do not live long enough-the peduncles abscise after 1-2 months, the plant being sterile. Many foliar outgrowths cease growing after a few months but remain alive as long as the leaf stays on the plant (1-2 years). Some foliar outgrowths on sterns are still living after 4 years. Most still have only one leaf of the bilaterally symmetrical juvenile begonia leaf form. No outgrowths on leaves and less than 1% of stem outgrowths develop a stem meristem and thus a succession of leaves, which though small are of the mature leaf form of this species. When a stem forms roots can be induced and a plantlet, separable from the parent plant, is formed. No vascular connection between the outgrowths and the parent plant ever develops. Instead a bulbous mass of xylem matures at the base of the outgrowth.

Thurston, E. L., and N. R. Lersten. Iowa State University, Ames-THE ONTOGENY AND HISTOCHEMISTRY OF STINGING HAIRS IN URTICA nrorca-e-Stinging hairs in Urtica dioica consist of a large stinging cell with an asymmetrical tip and a bulbous base which is embedded in a cup-like multicellular sheath (pedestal). The stinging cell is initiated first, br a protrusion of a single epidermal cell. The asymmetrica tip differentiates just after initiation. Further growth of the stinging cell is intercalary. Adjacent epidermal and hypodermal cells later divide and contribute to the pedestal. The nucleus of the stinging cell is about five times larger in diameter than nuclei of adjacent epidermal cells, suggesting polyploidy. The cytoplasm of the mature stinging cell contains numerous PAS-positive particles, several large vacuoles, and a greater amount of RNA than other epidermal cells. Other histochemical results during ontogeny will be discussed. Increased levels of succinic dehydrogenase in axils of some leaves, indicating sites of lateral bud initiation, are visible in late March. Bud primordia can be identified cytochemically as vegetative or reproductive by early June. During the 10 weeks following initiation, the fate of the bud primordia is not fixed. Some will abort and disappear completely, and others will cease development at a later stage and become latent. Only about half of.-j,he buds initiated fully develop. The proportion of developing buds which become vegetative or seed or pollen cones varies from tree to tree and from year to year'. Cytochemical differences between potentially vegetative and potentially reproductive apices have been studied. Levels of RNA, as indicated by pyronin-Y staining, are higher in reproductive than vegetative apices before these apices can be distinguished anatomically.

Majumdar, S. K., and P. S. Sabharwal. University of Kentucky, Lexington-c-Ixnccrrox OF VEGETA. TIVE BUDS ON INFLORESCENCE OF HAWORTHIA IN VIi'I«r-It is well known that monocotyledonous plants are difficult to grow in culture. The present study was conducted to investigate the growth potential of isolated organs of various species of Haworthia in vitro. The inflorescence axis bearing flowers was inoculated on White's basic medium containing coconut milk, kinetin and IAA. In some species the flower buds shrivelled within 20 days after inoculation. In others floral buds grew into mature flowers. From the axis of some of the shrivelled flowers appeared vegetative buds which looked like miniature plants. In some cases, the base of the inflorescence axis callused and immediately started differentiation into numerous vegetative buds. Rooting was also observed in some of these cultures. Pollen grains from in vitro-developed flowers of a completely male-sterile species were studied by aceto-carmine technique. In nature the pollen mother cells undergo normal meiosis and tetrad formation, but the pollen grains are sterile at maturity. The pollen grains produced in culture condition showed a higher percentage of fertility. are induced to undergo mitosis, cleavage, zoospore formation, zoospore discharge, and aggregation of zoospores into new coenohia upon the addition of fresh medium and exposure to white light. Red light inhibits release. The inhibitory effect of stale medium is relieved by the addition of nitrogen but not by calcium, phosphorus, magnesium or iron. Zoospores are released within a membrane which is confirmed in electron micrographs to be [Vol. 55 Developmental Section-eontinued the inner layer of the bi-layered wall of the parent cells. Zoospores swim for several minutes within the vesicle, aggregate in a disc, and become adherent to each other with an electron-dense material. The fine structure of the cell wall and other aspects of its nature will be discussed.

Greathouse, D. C., and W. M. Laetsch. University of California, Berkeley-EFFECTS OF GIBBERELLIC ACID ON THE DIMORPHIC BRANCHES OF THEOBROMA CACAo-The dimorphism of the branch system of 7'. cacao and the manner in which it arises was previously described. The orthotropic shoot of the seedling is characterized by a three-eighths phyllotaxy and the plagiotropic branches by a one-half phyllotaxy. As is the case with many tropical trees, the branches grow in flushes. A variable number of leaves expand with each flush and develop to maturity with concomitant elongation of adjacent internodes. Leaf primordia are initiated at a fairly constant rate. The effects of gibberellic acid on the branch system morphology and the flushing pattern of growth was studied. Gibberellic acid in lanolin was applied to the base of the shoot tip of orthotropic shoots in concentrations of 50 and 1000 mg/liter, These applications resulted in a marked increase in shoot length and a significant increase in leaf number. The phyllotaxy was not affected. A marked effect of GA on plagiotropic branches of various 'ages was not demonstrated. The implications of this differential effect of GA on the dimorphic branch system will be discussed.

Fosket, Elizabeth B., and O. L. Stein. Universityof Massachusetts, Amherst-CoMPARATIVE ANAT-OMY OF THE ilROOT APEX OF HEDERA HELIX-The juvenile and adult forms of Hedera helix can be distinguished by their leaf shape, phyllotaxy, growth habit, and ability to flower. Much of this must be the result of differential activity of the apical meristem or its derivatives. Yet very little is known about the structure and function of the apex of Hedera. Roche (1949) analyzed the phy,llotaxy of the adult and juvenile forms and briefly described the shoot apex of each .. She found differences in the pitch of the foliar helices and determined that the juvenile plant was characterized by the absence of an "anneau initial." Beakbane (1961) and Goodin (1965) dealt with stem anatomy primarily. Initial work in this laboratory on H edera attempted to distinguish the shoot apices of the two forms. It was found that the adult apex was larger than the juvenile and showed more variation in size during the plastochron. The, juvenile apex remained relatively flat throughout the plastochron, whereas the adult increased greatly in height. Preliminary work indicated that cell size was greater in the juvenile form. Various histochemical techniques were used in order to determine zonation.patterns. l{): 30 Fisher,. J. B. University of California, Davis-THE INTERCALARY MERISTEM OF CYPERUS ALTERNIFOLIUS -The culm of Cyperu8 alternifoliu8 L. is formed by the elongation of one internode which elevates a crown of leaves that contains short internodes. An intercalary . meristem (1M) is found in the basal fewom of the elongated internode which may' be over 1 m long in older -plants.

The culJh is well suited as am experimental subject for studies on the control of the 1M, since this meristem is active for several weeks. Growth substances were applied to the basal portions of the growing internode after the upper portion of the internode and the leaves _were' removed. Rates of internode extension were measured. GAa had. a marked effect upon increasing the rate of internode extension. The leaves of the crown and -their axillary buds are not a major source of growth stimulation for the 1M.

Peterson, R. L. University of California, Davis-COMPARATIVE ANATOMICAL STUDIES OF CYTO-KININ-AND AUXIN-INDUCED ROOT-BUDS IN OPHIOGLOSSUM PETIOLATUM-Root segments of Ophioglo88Um petiolatum, either with an intact apex or with the apex removed, are capable of regenerating buds. Application of eytokinins and indoleacetic acid at appropriate concentrations increases the number of buds formed on these root segments. A detailed anatomical comparison of induced buds for a wide range of concentrations of these growth substances has shown that all are endogenous in origin and are comparable structurally with buds normally occurring on roots of various species of Ophioaloseum. Each apical meristem, consisting of an apical cell and a few of its derivatives, appears somewhat sunken and is located below an air cavity formed by the breakdown of adjacent cortical cells. Leaf primordia are large in comparison to the small apical meristem, and vascular tissue differentiates basipetally in relation to them. Treatments with higher concentrations of benzyladenine and kinetin stimulate the root cortical tissue to proliferate into a callus-like outgrowth. Within this proliferation numerous bud apical meristems of normal anatomical structures are organized in close proximity. to each other. In addition, abnormally large starch-filled parenchyma cells are differentiated in root segments treated with high concentrations of kinetin. Comparisons between -rnduced root-buds and buds forming 1Il rhizome callus tissue of this species will also be discussed. The constancy of apical meristem organization and some of the factors involved in bud inception in this species will be considered.

Wolery, Gene. University of California, Santa Cruz-MORPHOLOGICAL CHANGES DURING TUBER FORMA-TION IN THE LIVERWORT GEOTHALLUS TUBEROsus-The vegetative stage of Geothallu8 tubero8U8 may produce a distinct morphological structure known as a tuber which serves as a means of perenniation and vegetative reproduction. The tuber, generally 2-3 mm in its largest dimension, develops in the midrib of the thallus. Pronounced changes occur within the cells of the midrib during tuberization, The normal cells of this region have many plastids with extensive lamellae and large quantities of starch, as well as numerous mitochondria, some dietysomes, and an extensive endoplasmic reticulum. The cells of the mature tuber, however, contain few indications of these organelles but have large quantities of storage materials especially in the form of lipids and proteins. A discussion of some of the changes that occur during tuber formation will be presented.

Session 5. Wednesday Afternoon. D. J. PAO-LILLO, JR., presiding.

Jones, W. H., and K. Yokoyama. NASA, Ames Research Center. Moffett Field, California-e-Paoro-MORPHOGENESIS -OF PTERIS LONGIFOLIA UNDER VARIOUS LIGHT SPECTRA ON A CLI~WSTAT-Pteri8 longifolia gametephytes grown on a horizontal at 3 RPH under blue, green, yellow, red and white light at 100 ft-c exhibited distinct photomorphogenic differences. Growth under white light was used as the control for comparison of changes induced by the various spectra. Blue light produces three-dimensional pro thalli when growth occurs in normal orientation. On'a horizontal clinostat blue light produeeatwo-dimensional prothalli with small marginal crenations, The meristematic apical notch was located to one side and produced asymmetrical thalli. The l /w ratio Used as an index of~owth approximated controls; however, area of prothalli and length and number of rhizoids exceeded that of the controls. Green light perpetuated two-dimensional prothalli formation preceded by development of a filamentous base. The basal filaments composed of 4-7 cells originated from the initial spore cells. The numerous rhizoids varied in length and were arranged linearly along the basal filaments. Yellow light stimulated unidirectional growth resulting in filamentous gametophytes. The I/w ratio increased with age. Two-dimensional growth was initiated under red light; however, prominent protrusions occurred in third dimensions from the prothallus. Thirty to 40 of these chlorophyllous filaments arising from the dorsal surface of the gametophytes were observed at 50 days. The dorsal\x located filaments developed from individual thallus ce\ls which apparently retained capabilities for additional protonemal formation. As observed in white light, archegonia developed within 40 days under blue, green, and red light but not under yellow light. Clinostat growth resulted in pronounced morphogenesis in all four specific light spectra when compared to stationary normal oriented growth under white light.

Weinberg, E. S. The Rockefeller University, New York-THE EFFECT OF INHIBITORS, OF PROTEIN AND NUCLEIC ACID SYNTHESIS ON DIFFERENTIATION OF THE GAMETOPHYTE OF ANEMIA PHYLLITIDIs-Germination of spores of Anemia phyllitidis can be induced in the dark by gibberellic acid (GA3) . The inhibitors of RNA synthesis, fluorouracil, 8-azaguanine, and actinomycin D (AD), do not inhibit or delay this germination. The inhibitors of protein synthesis cycloheximide and pfluorophenylalanine do inhibit the GA3-induced germination. The effect of AD on GA3 induction of antheridia was also investigated. The spores were allowed to germinate in the light and then transferred to the dark, at which time AD and/or GA3 were added. At all concentrations of AD used (50-200 ,ug/ml), suppression of antheridium production was observed and found to be correlated with AD concentration. By contrast, vegetative growth in the absence of GA3, as measured by cell number, was not inhibited at these concentrations of AD. Division of the central cell of the antheridium and development of the sperm are inhibited by AD to a greater extent than in the induction of antheridia. If AD is present during GA 3induced dark germination, some delay in the first vegetative-cell division is observed. Development of rhizoids is inhibited and the formation of antheridia is suppressed to a greater extent than when AD is added after lightinduced germination. Experiments on the effect of these inhibitors on the synthesis of RNA and protein are in progress and will be discussed. These studies demonstrate that once the meiotic process has been initiated, it is possible to provide conditions which are adequate for completion of the cycle. However, initiation of the meiotic process in vitro and completion of the developmental events in culture remain rare events. This paper reports observations made on young fern plants of Todea barbara in which sporangial development, the occurrence of meiosis, and the production of viable spores were induced in vitro on a simple nutrient medium. Meiosis is initiated in the sporogenous cells and proceeds to completion in vitro with the formation of viable spores. Sporangial development, meiosis, and the production of spores occur in plants which exhibit signs of senescence. Fertile leaves are characterized by a reduction in chlorophyll concentration and total cellular nitrogen when compared to sterile leaves. The data suggest that the process of sporogenesis may be correlated with a reduction in metabolic activity of the leaf.

Rier, ). P., and D. T. Beslow. Howard University., Washmgton, D.C.-SUCROSE CONCENTRATION AND XYLEM REGENERATION IN ISOLATED INTERNODES OF COLEUS BLUMEI-Wounded internodes of Coleus blumei grown inverted or upright on agar containing a wide range of sucrose concentration were examined for quantitative and organizational responses of xylem regeneration in their wound areas. When sucrose was eliminated no xylem regeneration was observed. Beginning with 0.5% sucrose, the amount of xylem regeneration increased with an increase in the sugar concentration TIp to 7.5%. When indoleacetic acid (2 ppm) was added with the sucrose,the amount of regeneration was increased approximately one and one-half times. The lengths and secondary markings of newly formed vessels varied with the composition of the experimental media. Changes in the orientation of the internodes on the media effected differences in the organizational pattern of regenerated xylem.

Randolph, 1. A., J. P. Rier, and L. Blake.

Howard University, Washington, D.C.-LEAF ABSCISSION IN COLEUS BLUMEI-Leaf abscission in Coleus blumei was studied with specific emphasis on the role of the Iower leaves and the apical bud in conjunction with indoleacetic acid (IAA) and gibberellic acid (GA) on the abscission of the first three petiolar pairs. A statistical evaluation of the results indicated that bud replacements with lAA and GA effect abscission of upper debladed petioles. IAA inhibits and GA enhances abscission. When both the bud and lower leaves are present, abscission of upper debladed leaves is enhanced but not as much as with GA in place of the apical bud.

Scott, T. K., and M. B. Wilkins. University of Nottingham, U.K.-POLAR TRANSPORT OF AUXIN IN ZEA ROOTs-The movement of auxin was investigated in root segments of Zea mays L. 'Giant Horse Tooth,' using l-CH indole-3-acetic acid and the classical agar donorreceiver method. Twenty 6-mm sub-apical segments harvested from 65-hr-old seedlings were placed vertically between a single donor and a single receiver block. At least 10 times as much radioactivity was recovered from an apical receiving block than from a basal one after a transport period of 12 hr, when the concentration of IAA in the donor was 0.1 rmr, There is, therefore, an acropetal polar flux of auxin through the segments. This conclusion is also supported by the distribution of radioactivity in the tissues. The dependence of the polar flux upon metabolism has been determined under conditions of low temperature and anaerobiosis.

3:45 PO)lpei, R. W., and T. K. Scott. Oberlin College, Oberlin, OhIO-THE EFFECT OF LIGHT ON THE MORPHOLOGY AND ANATOMY OF INHIBITED LATERAL BUDs-The size of lateral buds and the nature of their bud traces have been analyzed at node number 2 of intact 'Alaska' pea seedlings exposed daily to white or red light or maintained in the dark. In all cases buds enlarge slightly but significantly for a I-week period after the emergence of the epieotyl from the cotyledons. Following this all buds persist in an inhibited state. By clearing whole segments of tissue it has been possible to locate and measure bud traces in situ. Complete traces (continuous from the largest bud to the stem vascular bundle) first occur prior to the cessation of bud growth in seedlings exposed to white and red light. It takes as much as a week longer for complete trac(,s to appear in seedlings kept in the dark. This delay apparently results from a slower differentiation of xylem and from a disruption of the trace by stretching. Cases of disruption and repair of disruption through the formation of new xylem bridges will be described. These observations indicate that the presence of a complete bud trace is not necessarily a primary factor in the "release" of a bud from an imposed apical dominance. root tips were grown on an agar-solidified medium containing modified White's minerals, casein hydrolysate (500 ppm), tuber extract (10%) and 2,4-D (0.05 ppm), and the effect of blue light, red light and unfiltered white light on the chlorophyll formation were studied. The roots grown in white light turned green in color in 4-6 weeks, whereas in blue or red light, localized green color occasionally appeared. The chlorophyll contents, as determined by the acetone-extraction spectrophotometric method, were found to be the maximum in unfiltered light (21.1 nanograms/milligram), followed by blue (8.5 ng/mg) and red light (8.3 ng/mg.) In all the light treatments the chlorophyll a contents were higher than chlorophyll b; however, in red light this was' reversed. In Murashige and Skoog's medium supplemented with NAA (0.2 ppm) and yeast extract (1000 ppm), certain nodule-like structures developed on the roots. If maintained under continuous high light intensities these nodules had a tendency to turn green in color.

Caruso, J. L., and Elizabeth G. Cutter. -Universityof California, Davis-DEVELOPMENTAL AND EXPERI-MENTAL MORPHOLOGY OF THE STELE OF ALEAFLESS TOMATO MUTANT-The reduced form of the lanceolate mutant in tomato is a small green cylinder which lacks cotyledons, foliage leaves and an organized shoot apex. The reduced plant is morphologically equivalent to a hypocotyl with roots. The stelar morphology at lower levels of the mutant hypocotyl is similar to that at comparable levels in normal, but it differs markedly in the middle and upper portioes. The increase in size of reduced plants grown on a nutrient medium under sterile culture conditions is the result of a proliferation of cells in the central cylinder. There is a Ininimal amount of xylem differentiation, and no vascular cambium is present. When an actively growing shoot tip of normal is grafted onto a decapitated mutant hypocotyl, this random proliferation does not occur. The increase in girth of the grafted mutant hypocotyl results mainly from the activity of a vascular camhium.

Soetiarto, S. R., and Ernest Ball. North Carolina State University, Raleigh-EXPERIMENTAL BISECTION OF THE FLORAL APEX OF PORTULACA GRANDIFLORA-The regenerative ability of the floral apex depended upon the stage at which it was bisected. From the first three stages of flower differentiation there resulted two new floral apices with complete floral appendages, except for sepals; the fourth stage regenerated into two incomplete flowers, each with complete ovary, but lacking new sepals, petals and stamens above the cuts. The last two stages resulted in two flower halves. In addition to the restricted and diminishing regenerative potential of the floral apex in organ restitution, there was a restricted amount of cell division beneath the wound surfaces which likewise decreased with the age of the meristem. These organogenic and histological responses to wounding and hisection are thus liInited at the outset, and, concoInitant with the determinate nature of the floral apex, decrease with aging of the meristem. They may be contrasted with the comparatively great histological response to wounding in the shoot apex, by the production of abundant cell divisions and new cells beneath a cut surface, and by the unlimited production of new foliar primordia by a shoot apex regenerated from a portion of an original one. globeberry were fixed for light and electron microscopy at several stages in the development of the mature fruit color. As the green fruits undergo maturation they pass through a very brief yellow stage, then through an extended orange stage, and they finally attain a deep red-orange in the ripe fruit. During this sequence very little change in size occurs. As the chloroplasts change to chromoplasts the original plastid structure is lost; thus at an intermediate stage only the plastid envelope and a few thylakoids are present. As development proceeds new series of thylakoids form in bands near the margin of the plastid and polyhedral fibrils begin to arise in the stroma. At first the fibrils are random in distribution, but they become ordered into bodies which increase in size. The bodies consist of several hundred hexagonally packed polyhedral filaments in arcuate arrays. The individual filaments are clearly polyhedral in cross section and of an undeterInined but extended length. With KMnO, fixation the fibrils are about 200 A in diam and show a distinct lumen about 50 A in diam; with glutaraldehyde-osmium fixation they are thinner and do not exhibit a lumen. As development progresses "crystals" begin to appear in the chromoplasts, In the light microscope these crystals consist of dense deposits of yellow or orange pigments and are largely responsible for the color of fruit. In the electron microscope the crystals are not homogenous but are complex structures which appear to be formed by the union of subunits initially found free in the stroma. As these crystals develop the paracrystalline arrays of fibrils diminish in size and number. Growth of the crystals causes modification of the plastid shape; when mature the plastids may be elongate, triangular or banjo-shaped.

Homer, H. T., Jr. Iowa State University, Ames-SPOROPOLLENIN FORMATION AND SECRETION BY TAPETAL CELLS-Production and secretion of sporopollenin by tapetal cells in the form of granules, plaques or Ubisch bodies have been frequently observed in sporangia and anthers of the Embryophyta. The site of synthesis within tapeta is still questionable, however. Tapeta in Selaginella megasporangia and mierosporangia and Citrus anthers produce different types of sporopollenin monomers which, when secreted, polymerize into granules or plaques. Production of the monomers appears to be associated with the proliferation of the Golgi apparatus and endoplasmic reticulum during the tetrad and separate microspore periods. In Selaginella the tapetal walls remain intact during sporopollenin formation, whereas in Citrus these walls are dissolved away first. In Citrus Golgi vesicles then appear to fuse with the tapetal plasmalemma, depositing the monomers to the outside. These monomers polymerize, forming smooth, spherical sporopollenin granules. The monomers in Selaqinella sporangia appear fibrous at first; then they aggregate into granules or plaques in the locule. Sporopollenin in this form then accumulates on the spore exine, forming the sculptured pattern, while in Citrus the sporopollenin seems only to add to the sculptured pattern already produced by each microspore. The implication of these results will be compared with previous studies. o\.EMANTHUS KATHERINAE Baker-During telophase of microspore mitosis, one set of chromosomes aggregates opposite the microspore aperture and is surrounded by very few organelles. The other chromatin mass and most of the cell's organelles lie adjacent to the aperture. Cellwall formation partitions the new pollen grain into two cells of unequal size, vegetative and generative. The generative cellia the smaller of the two and always lies opposite the aperture. Initially the wall which surrounds the generative cell is attached to the pollen wall. The nucleus is highly condensed and nucleoli are present. A scattering of mierotubules as well as mitochondria, Golgi, endoplasmic reticulum and ribosomes can be seen in the cytoplasm. Following separation of pollen wall and generative wall, the generative cell moves towards the center of the pollen grain. At this time mierotubules become more abundant and are aften associated with areas of finely fibrous material. As the generative cell and its nucleus assume an elongated form, the chromatin becomes more highly condensed and nucleoli disappear. The microtubules become aligned along the wall with their long axes parallel to the long axis .of the cell. This arrangement of microtubules persists throughout pollen development and is also present when the generative cell has moved into the pollen tube. The absence of prolamellar bodies in chloroplasts of tissue cultures that have been grown in the dark and placed in the light on a normal medium has been previously reported. Although the chloroplasts that result are identical to those found in leaf tissue, the prolamellar body does not take part in their development. When dark-grown callus tissue is placed on a medium lacking kinetin, the plastids fail to develop into chloroplasts, but a structure similar to the prolamellar body is observed. Buds induced from callus tissue by high kinetin concentrations in the dark form etiolated shoot systems whose proplastids contain prolamellar bodies. The presence of the prolamellar body in the development of the chloroplast in these tissues may be determined by levels of cytokinins in the tissue.

Hoefert, L. L. Crops Research Division, U.S.D.A., Utah State University, Logan-ULTRASTRUC-TURE ,OF POLLEN DEVELOPMENT IN SUGAR BEE~tages in pollen development in Beta were studied with the electron microscope. Cytoplasmic features are compared to previous studies, and the reticulum complex and residual spindle fiber microtubules are described. Stages in wall ontogeny, including proposed schemes of production and incorporation of exine material (or sporopollenin), will be presented. The only ultrastructural account of fruiting in S. commune was directed solely towards basidiospore formation and utilized KMn04 fixation which does not adequately preserve certain structures. Consequently, we have initiated parallel investigations of the histology and ultrastructure of dikaryotic fruitbody development in S. commune. Tissue fixed in FAA was embedded and sectioned, then stained with a modified Conant's quadruple stain for bright-field microscopy. Glutaraldehyde followed by OS04 fixation and leadcitrate staining was employed for electron microscopy. Formation of dikaryotic fruitbody primordia was characterized by the appearance of loose aggregates of intertwined hyphae. Stipe differentiation included proximal b\!!POus cells within an irregularly organized mycelial n. e;.work, with thick-walled parallel elements in the Inidpot,liion of the apex. Ultrastructural features of cells comprising the stipe included thick cell walls bounded by an amorphous extracellular matrix. Intercalated vacuoles and some free ribosomes were the dominant features. The sub-basidial area of sporulating fruits contained thick-walled oells~, abundant electron-dense vacuoles, and ribosomes. Unidentified arrays of membranes were also conspicuous. The basidia, in contrast, were thin-walled elements lacking ali-extracellular matrix. These cells contained abundant ribosomes, glycogen particles, mitochondria, electron-lucent vacuoles, and nuclei containing nucleoli and tripartite structures resembling synaptinemal complexes.

Waaland, J. R., and D. Branton. University of California, Berkeley-ULTRASTRUCTURE OF GAS VACUOLE MEMBRANES IN BLUE-GREEN ALGAE AND HALO-PHILIC BACTERIA-Gas vacuole membrane ultrastructure is examined by means of the freeze-etch technique, shadowing, and negative staining in intact cells and in preparations of isolated gas vacuoles. The morphology and size of the gas vacuoles are different in Nostoc muscorum (1.3 X 0.1 J1o) than in Halobacterium sp. (0.5 X 0.3 J1o). The ultrastructure of the gas vacuole membranes IS similar in these organisms; the membranes are composed of globular subunits of approximately 40A diam arranged in rings perpendicular to the axis of the gas vacuoles. Freeze-etch studies show that the membrane-gas interface which is characteristically seen in freeze-etch preparations presents the globular substructure. Deep-etching experiments and shadowed preparations of isolated gas vacuoles reveal the structure of the cytoplasm-membrane interface which also presents a surface composed of globular subunits.

Goff, C. W. The University of Texas, Austin-A DEVELOPMENTAL CHANGE IN THE ORGANELLE LOCALIZA-TION OF INOSINE DIPHOSPHATASE ACTIVITy-Inosine diphosphatase reactions of the Gomori type were carried out on Allium cepa root tips and the resultant leadphosphate precipitate localized by electron microscopy. The essentially linear arrangement of cells in this system [Vol. 55 Developmental Section-continued allows changes in morphology or chemistry to be correlated with development. The enzyme activity was found only in the Golgi apparatus in the root cap. For several hundred microns basipetally in the root the reaction p-roduct was also limited to the Golgi apparatus in most, if not all, tissue types. Above this region, reaction product was additionally localized within the endoplasmic reticulum and the reaction in the Golgi apparatus was decreased in amount. Additional cytochemical studies still in progress, including those for detection of other enzymes, may elucidate possible physiological correlates of this developmental change. (2) an extensive temporal acropetal decrease in their concentration. The decrease and change of location of the lipid bodies within the cells were correlated with certain aspects of cellular differentiation by light and electron microscopy. The lipid composition of these bodies isolated by centrifugation was determined by' thin-layer chromatography. Because of the inherent difficulty in isolating lipid bodies from excised shoot apices, morphologically and histochemically similar bodies found in the scutellum were used for analysis. Neutral lipid, notably triglycerides, with relatively small proportions of sterols, phospholipids, and protein were the major components. Ultrastructural observations of both the isolated and in situ lipid bodies confirmed the nature of the isolated preparation and also showed a boundary interface which was not the typical trilamellar unit-membrane structure.

Kelley, C. B., and W. T. Doyle. University of California, Santa Cruz-AsPECTS OF SPOROPHYTE DEVEL-OPMENT IN SPHAEROCARPOS DONNELLu-Ultrastructural and histochemical changes during sporophyte development . were studied with the aid of electron and light microscopy. The sporophyte consists of three parts: the foot, which is embedded within the gametophytic tissue; the seta or stalk; and the capsule, within which the spore mother cells and nutritive cells will eventually develop. The capsular cells are initially indistinguishable from one another. They: contain small vacuoles and abundant cytoplasm WIth numerous mitochondria, proplastids, some dictyosomes, endoplasmic reticulum which is often oriented in arrays parallel to the cell wall, and numerous vesicles which occur on both sides of the plasmalemma. Differentiation can first be detected ultrastructurally about 13 days after fertilization. By 15 days differentiation between spore mother celIs and nutritive cells is clearly discernible by light microscopy. At this time the nutritive cells are highly vacuolate, contain many plastids with much starch, and are often multinucleate. In contrast, the spore mother cells have an extremely dense cytoplasm fewer starch-containing plastids, and many lipid vesicles. The increase in volume of the spore mother celIs which occurs prior to meiosis appears to be caused by an increase in cytoplasmic components, particularly the lipid-containing vesicles, rather than by vacuolar expansion. internodal epidermis arises by a sequence of three cell divisions in short epidermal cells. The first two divisions, resulting in formation of two subsidiary cells, occur in the long epidermal cells on each side of a guard cell mother cell (GCMC). Microtubules occur in two bands adjacent to the GCMC wall where the subsidiary cell plate will join the parent cell wall. The third division (longitudinal) occurs in the GCMC, resulting in the formation of two guard cells. The cell plate usually fails to develop completely to the GCMC wall. This leaves a well-defined pore between the two guard cells. During development of subsidiary celIs, a single large vacuole forms in each cell. During guardcell differentiation, the nuclei become greatly elongated, small vacuoles form in the ends of these cells, and plastids with poorly developed grana lamellae become apparent. Atthe ends of the guard cells, the outer cell walls become substantially thickened. Numerous microtubules appear along the center portion of the wall common to the two guard cells. At this same locus, after the appearance of these microtubules, the wall forms a thick pad. Lysis of the middle lamella, which results in stoma formation, appears to occur concomitantly with this wall thickening. These observations indicate that subsidiary and guard cells of the stomatal apparatus, though similar in form and in the kinds of organelles present initially, follow remarkably divergent pathways of differentiation during development of the stomatal apparatus. Session 1. Friday Morning. J. P. RIER, presiding.

Murashige, T., and R. T. Nakano. University of California, Riverside-THE LIGHT REQUIREMENT FOR SHOOT INITIATION IN TOBACCO CALLUS CULTURE-Experiments with Nicotiana tabacum callus disclosed that light is critical in the initiation of shoots. Root initiation also showed optimum light effects. The light requirement for shoot initiation was satisfied by a nutrient medium involving increased phosphate and additions of L-tyrosine and adenine sulfate.

Thorpe, T. A., and T. Murashige. University of California, Riverside-SoME HISTOCHEMICAL CHANGES UNDERLYING SHOOT INITIATION IN TOBACCO CALLUS CULTURE-A comparative histochemical study of changes in nucleic acids, proteins and carbohydrates was performed on freeze-substituted samples of tobacco callus cultured under shoot-forming and non-organ-forming conditions. There was no apparent change in the DNA content per cell, whereas more RNA seemed present just prior to and during the initiation of organized structures. Difference in the protein contents was pronounced only at the time of formation of meristemoids. The most dramatic finding was the heavy accumulation of starch in shoot-forming tissue; the accumulation preceded any" organ formation and was mainly in regions which ultimately gave rise to primordia.

Rangan, T. S., and Toshio Murashige. University of California, Riverside-IN VITRO INDUCTION OF NUCELLAR EMBRYOS IN MONOEMBRYONIC CITRus-Experiments were conducted to obtain adventive embryos from the nucelli of three monoembryonic citrus: C1"truS grand is, C. limon 'Ponderosa' and C. reticulata X C. sinensis. Seeds were dissected from young fruits approximately 100-120 days after pollination. The nucellus and the zygotic embryo were excised from the ovule. The zygotic embryo was discarded, whereas the nucellus was planted on a medium supplemented with either a combination of adenine sulfate (25 mg/Iiter), NAA (0.5 mg/liter) and orange juice (fiii') or malt extract (500 rag/liter). In about 4 weeks some of the nucellar explants developed embryos. Histologic preparations confirmed the nueellar origin of adventive embryos. When transferred to a fresh medium of the same composition, the embryos developed into seedlings with well developed roots and a few leaves. SUbsequently, the seedlings were transferred to vermiculite + Hoagland's nutrient solution where they continued their growth. show promising characteristics for studies on the physiology of growth of higher plant cells. Now 10 months in culture, the cells display a rapid growth rate, do not differentiate organs, produce dense cell suspensions in liquid medium, develop prominent chloroplasts in the light, and when plated on an agar medium 40% or more of 1-5-celled units grow into multi-cellular colonies within 7 days. Studies in progress are aimed at further improving the growth rate, cell separation, and plating efficiency through manipulation of the nutrient medium and the environment. These cells have displayed the behavior described above for the past 5 months, and their nuclei are now aneuploid about the 4n number. In early passages when most cells had 2n or 4n nuclei, there was little cell separation and adventitious roots were produced prolifically. Just before roots ceased being produced by the main cell line, a subline was started using root tips or root segments as transfer inocula. The nuclei of root-tip cells by that time were all tetraploid. Placed in a medium containing auxin (routinely used in maintaining the root subline), these very slender roots branch freely, and after a lag period the branches elongate at a rate of about 1 cm per week. Large mats of roots are thus produced during a monthly subculture period. Factors influencing root development in this subline are being investigated.

Davidson, D., and W. R. Sharp. Case Western Reserve University, Cleveland-CALLUSES AND TERA-TOMAS IN COLCHICINE-TREATED PLANTS-Shoot apices of cabbage and tobacco plants were treated with lanolin paste containing 2% colchicine. Several changes were noted in the treated plants. Those dealing with the long term changes in particular will be considered. In treated cabbages growing shoots had formed within 7-10 days. After 3 months calluses appeared on these plants. The calluses were first formed close to the site of treatment, but they have continued to form on growing shoots, where they grow out of leaf scars. Some calluses gave rise to root-like outgrowths, but these never exceeded 5 mm in length. Six months after the original colchicine treatment, shoots developed from calluses' some plants have produced several shoots. These growth changes are similar to those found in genetic tumors. The induction of abnormal growth cannot be attributed solely to the colchicine treatment since similar changes have occurred in cabbage plants that were decapitated when other plants were treated with colchicine. Tobacco (N. glaucalangsdorffii, amphidiploid plants) has also been treated with colchicine-lanolin paste. Teratomatas and lateral branches have formed on treated plants. The teratomatas have formed both at the apex of the treated shoot and below the first leaf. It is well known that this particular abnormality would develop on these hybrid plants after flowering, or can be induced by irradiating them. The fact that they are developing on young plants with 5-8 fully formed leaves that are also giving rise to lateral branches indicates that the change induced by colchicine is operative at a site unrelated to that involved in the induction of polyploid cells. These results suggest that a change occurs in the ability of shoot apices to control lateral bud formation. Such a change may be related to an effect on levels of growth factors. This possibility will be discussed.

Norstog, K. Northern TIlinoisUniversity, DeKalb -PHYSICAL FACTORS IN RELATION TO DEVELOPMENT OF CULTURED BARLEY' EMBRYOs-Barley embryos excised when slightly less than 20% of their full-term length (i.e., about 5 mm) responded variously to culture on media differing only in sugar concentration, or when grown under differing intensities of light, or at differing temperatures, or combinations of these. Precocious germination-the assumption of a phase in which cellular elongation is a predominant growth expression-occurred at low temperature (20-25 C) in dark or low light intensity (20 ft-c), and was more characteristic of embryos cultured on low-sugar media (0.1--0.15 M sucrose). Embryological growtha phase in which cellular division is predominant and cellular enlargement is minimal-occurred at higher temperature (25-30 C) and at higher light intensities (100-200 ft-c), and with media having high sucrose levels (0.3-0.35 M). Intermediate responses were noted when any or all of these factors (sugar concentration, temperature, light) were moderate (0.2 M, 25 C, 20-50 ft-c). Con. tinuous culture at a temperature of 35 C was lethal. The inhibition of precocious germination by high light, high sugar, or high temperatures was reversed both in lightand dark-grown culture by addition of 1-5 mg/liter gibberellic acid to the medium. Precocious germination in vitro is not caused exclusively by low sugar concentration as formerly supposed, since it may be suppressed by culture at high light and temperature (200 ft-c; 30 C). It appears to be related to the action of gibberellin or gibberellin-like substances.

Venketeswaran,S., and W. H. Home. University of Houston, and Brown and Root-Northrop, Lunar Receiving Laboratory, Houston, Texas-ISOLATION AND DEVELOPMENT OF CORN-TISSUE CULTURE FROM DIPLOID ROOTs-Adventitious root explants of field corn (Zea mays var. A-204) have been isolated and maintained as tissue culture in a salt-sucrose medium containing 1 X 10-6 M of both 2,4-dichlorophenoxyacetic acid and a-napthalene acetic acid. This medium was usually supplemented with 10% coconut milk. The explants initiated masses of proliferating cells resulting in swollen nodules at regular intervals along the original root explant. Isolation of these proliferations resulted in the formation of large masses of undifferentiated, homogeneous cells with a relatively high growth rate, These occasionally gave rise to further adventitious rootlets which repeatedly proliferated into masses of callus cells. Histological examination indicated rapid cell divisions in the periphery of the swollen nodules and in the callus cells. Electronmicrographs of the cells revealed normal cellular details and organelles. Among these were numerous double-membraned organelles containing darkly stained storage products of possible starch or lipid composition. Detailed investigations are in progress and will be presented. White's minerals, sucrose (3%), 2,4-D (1 ppm) + kinetin (0.1 ppm) and yeast extract (1,000 ppm), and the effect of gamma and ultraviolet radiations on their growth has been studied. Three-day-old suspension cultures containing free cells, aggregates of cells, and small callus [Vol. 55 Developmental Section-continued masses were subjected to C0 60 gamma-radiations at various doses (5~Or, 1, 2, 5, 10, 20, 30, 40, and so kilo r~s) @ 200r/mmute, and grown for 4 weeks in diffuse light. At 500.1' there was a slight stimulation of growth as assayed by tissue volume, fresh weight, dry weight, and mitotic index. However, from 1 to 10 Kr there was a gradual decrease in growth. The cells exhibited a wide variety of shapes and sizes, mitotic inhibition increased polyploidy". degeneration of cytoplasm, and reduced plating efficiency, At 20 and 30 Kr, growth was drastically reduced and inhibited; severe killing and cessation of growth occurred at 40 Kr. The color of the callus continued to darken with increased dosimetry. The radiosensrtivity of the tissue depended on the age of the inoculum. For ultraviolet treatment suspensions containing free c«;lls and small-cell aggregates were first exposed in petri dishes to 500 to 4,000 ergs @ 50 erg mm-2 sec-I, transferred to Erlenmeyer flasks, and incubated in the dark. Generally, UV exposure resulted in inhibition of cell c!ivision and grow~h. However, cultures grown in the light. }OIlO.Wlllg U\ expo~ure.showed improved growth, accompanied by a reduction m cell abnormalities. Data on the changes in DNA, RNA, and protein levels will also be presented. EUROPEAN GREY POPLAR-A friable strain of European grey poplar (Populus canescens) has been cultured since October, 1966, on Wol~er's agar medium containing 0.5 mg/liter of. 2,;4-D. ThiS yello~, spreadable tissue dissoeiates easily in shake cultures into single cells and small colonies and appears to multiply by budding. Tissue Isolated from the same 6-month-old seedling but grown on Wo~ter's medium containing 0.04 mg/Iiter~f 2,4-D and 1 mg/liter kinetin, grew slower and was firm and white. A colorless! friable strain developed spontaneously from the firm white tissue but did not grow as rapidly or dissociate as easily as the yellow strain growing on the high-2,4-D medium.

10:45 Smith, C. W., and S. M. Siegel. University of Hawaii, Honolulu-BIOLOGICAL EFFECTS OF GLYCINE-Glycine, believed to be a major constituent of the primaevaloceans, IS the Simplest amino acid which imparts o specific structural features in proteins. Feeding organ-IS~wIth. high concentrations of such a simple amino acid could induce the incorporation of glycine into unusual metabolic and biosynthetie processes. Altered biosynthesis could lead to more primitive cellular states and the reversion of certain characters t~their "primitive ex-pressio~." In addition the hypertonicity of high conce.ntrat~ons~ust also be eonsidered. Organisms vary widely m their tolerance to hI,ghconcentrations of glycine, but some mutagemc effects III fungi and morphogenetic effects in Bouesinqaultia gracilis and the crustacean A rtemia salina have been observed. These and other responses will be discussed. The silica is deposited on the inner cell-wall surfaces between the walls and the respective adjacent cell membranes. This suggests that large silica deposits so formed might be replicas of cell wall surfaces and cell configuration. Three-dimensional carbon replicas of graminae opaline phytoliths which show that the silica is deposited regularly but non-incrementally on most epidermal cell wall surfaces were prepared. Intact stomata are preserved or replicated as phytoliths; other cells as well are accurately replicated in· silica. Opaline phytoliths are generally amorphous in appearance and without any ordered surface patterns; undulations and knobby projections are common. Graminae opaline phytoliths are formed within a polysaccharide mold, whereas opaline sponge spicules are deposited upon a polysaccharide endoskeleton. Controlled petrifaction may be an economical means for grasses to attain rigidity with minimum expenditure of photosynthate.

Paolillo, D. J., Jr. University of Illinois, Urbana-FURTHER STUDIES ON CHLOROPLAST THREE-DIMENSIONAL ULTRASTRUCTURE-The model described for the three-dimensional structure of the grana of Zea mays mesophyll plastids consists of multiple frets helically wound around each cylindrical stack of granum compartments. This model has now been extended to the grana of chloroplasts in bean, hemp, pea, spinach, tobacco and elodea plants. The model is consistent with the arrangement of grana within the whole chloroplast.

Preliminary results indicate that all of the helices in a plastid are wound in the same direction. The intricacy of the system suggests that many continuities among membranes are established as the result of fusions during the development of grana and fret membranes. Inclusions composed of rod-shaped particles were observed in the crtopla.sm of sugarbeet leaves infected with beet mosaic VIrus. The particles correspond in size to those obtained by other workers using leaf-dip techniques (15 mIL X 750 mIL). These cytoplasmic inclusions are present in vesiculated cytoplasm, or they may be present in regions that do not show vesiculation. Inclusions and rough endoplasmic reticulum often are in close association in infected cells. Partially purified preparations also were examined with the electron microscope. Particle morphology, relative infectivity, and cytological aspects of the infection will be discussed.

Gantt, Elizabeth, and S. F. Conti. Smithsonian Institution, Washington, D.C., and University of Kentucky, Lexington-ISOLATION OF PHYCOBILISOMES-Previous evidence suggested that small granules (300-400 A diam) which are found attached to the chloroplast lamellae of Porphyridium cruentum contained phycobiliproteins. In order to. ascertain the nature of the granules and to see whether or not they indeed contained the phycobiliproteins, it was necessary to isolate them. The isolation procedure involved the use of electron micro-scopy, density gradient centrifugation, and spectrophotometry. Cells, suspended in 0.1 M phosphate buffer at pH 6.8, were disrupted in a French pressure cell. The material was then treated with 0.2% deoxycholate (10-15 min) to free the granules from the photosynthetic lamellae. Glutaraldehyde was subsequently added to stabilize their structure. Lamellar material and other cell debris was removed by centrifugation, and the red supernatant was placed on a sucrose density gradient (0.2 M-2 M). Following centrifugation at 53,500 X (J in a swinging bucket rotor, phycobiliproteins were present in a top pink layer, right below the meniscus, and a purple layer, in the middle of the gradient. Samples were removed along the entire gradient and examined by electron microscopy. Granules were present only in the purple layer (middle). The absorption spectrum of this layer showed a broad major peak at 540-563 mIL (phycoerythrin) and a smaller peak at 620 mIL (phycocyanin). The top pink layer contained some dissociated subunits and other unidentified UV absorbing substances. Since the granules contained the phycobiliproteins they have been given the name phycobilisomes (phycobiliprotein bodies). It should be noted that the location of the phycobilisomes on the lamellae is significant, because the phycobiliproteins play an important role in photosynthesis by transferring excitation energy of absorbed light. Phycobilisomes have been observed in several members of the Rhodophyta and Cyanophyta.

Rickson, F. R. University of Wisconsin, Madison-HISTOCHEMISTRY AND ULTRASTRUCTURE OF BELTIAN BODIEs-Beltian bodies are small structures found at the tip of the rachis and pinnules of certain tropical species of A cacia. Ants living on the tree harvest the Beltian bodies, which, along with a sugar solution from petiole glands, constitutes the only food taken by the inhabitants. In return the ants protect the tree from molestation. In 1877 Francis Darwin speculated on the evolutionary history of Beltain bodies and concluded that they were derived from serration glands, as found on the leaf margins of other plants. Cytochemical data indicated a 'high protein content for the cortical cells of these structures. At the ultrastructural level massive aggregations of tubules were found in the cytoplasm and nucleoplasm. They have a diameter of 76--77A which separates them from other reported cytoplasmic tubules. Micrographs of these tubules and other cytoplasmic components will berresented, and their implication in protein secretion wi! be discussed.

Arnott, H. J., S. W. Rosso, and K. M. Smith.

Beta') seedlings about 6 inches in height were inoculated with a common strain of tobacco mosaic virus (TMV). Portions of leaves were fixed at various time intervals thereafter in glutaraldehyde/acrolein followed by osmium tetroxide. Only leaves produced after inoculation and displaying typical TMV symptoms were fixed; care was taken to process the different-colored portions of the leaves separately. In yellow-white areas of the leaf both normal and abnormal plastids were found. The abnormal plastids could be characterized as "reticulate," "globulate" "thylakoidal " and "supergranal" however intergradations betwee~these four types w~re also present.

The abnormal plastids were often enlarged and sometimes showed large accumulations of osmiophilic bodies and/or peculiar membrane configurations. Many of the abnormal plastids are morphologically similar in ultrastructure to mutant plastids reported in recent studies. Both abnormal and normal plastids were found in single "mixed" cells; [Vol. 55 General Section-continued in fact, such phenotypic variation was characteristic of palisade parenchyma cells of the yellow-white areas. Normal and abnormal plastids were found in about equal numbers in many cells of these areas. Many "mixed" cells also exhibited masses of TMV particles as well as other inclusions characteristic for TMV infections. The nature and differences between abnormal plastid types will be discussed and a hypothesis which attempts to explain these findings will be presented.

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3:35 Falk, R. H. The Biological Laboratories, Harvard University, Cambridge, Mass.-THE FRACTION I PROTEIN OF CHINESE CABBAGE-A new procedure for the isolation of chinese cabbage Fraction I protein employing ammonium-sulfate fractionation and concentration and sucrose-density gradient centrifugation is described. Various physical parameters of chinese cabbage Fraction I protein are reported: the protein has an S20 of 17.6; a molecular weight of 595,170 g/mole and 600,000 g/mole (two methods) has been determined; a minimum molecular' weight of 8,641 g/mole was calculated from amino acid analysis of the protein; electron microscopic examination showed the protein to be made up of 100-115 A particles. Chinese cabbage Fraction I protein has been shown to exhibit ribulose 1,5-diphosphate carboxylase activity. Chinese cabbage Fraction I protein was not found to be particularly effective in eliciting an immune response in rabbits. A titer of 764 was usual.

Fluorescein-labeled anti-Fraction I protein experiments support the view that Fraction I protein is associated with the chloroplast. Localization of Fraction I protein with ferritin-labeled antibody was unsuccessful.

Simmons, E., K. Mattimoe, D. W. Schwab, and ]. Scala. Fundamental Research, Owens-Illinois, Inc., and Institute of Medical Research, Toledo, Ohio-HYDROLYTIC ENZYME EI,ABORATIONS OF VENUS'S FLY-TRAP-The digestive process of Venus's flytrap has been studied with histochemical, electron microscopic and biochemical techniques. Digestive gland cells undergo changes which are commonly observed in the mammalian pancreas. Zymogen-containmg granules of the digestive gland cells disintegrate and release the proteolytic enzymes into the closed trap. This process can be initiated by feeding the plant meat or by the proper use of drugs which normally bring about the analogous reactions in the pancreas. Phosphataees, proteinases, and peptidases in the digestive fluid have been assayed by standard biochemical techniques. The changes observed at the fine structural level are most striking in the Golgi complex, endoplasmic reticulum, mitochondria and other cellular organelles. The entire digestive process requires from 7 to 10 days as originally described by Charles Darwin. Data will be presented covering each of the above considerations.

Brennanv }, R. Massachusetts State College, Bridgewater-THE FORMATION OF "COLCHICINE TUMORS" ON THE'ROOT Tips OF PHLEUM PRATENSE SEEDLINGS-Application of colchicine causes the development of swollen areas or "C-tumors" in actively growing root tips of young timothy grass seedlings. Light microscopic studies of these abnormalities reveal that cell division is halted but that cell enlargement continues, progressing apically into the former region of cell division. The resultant growth is not normal, however, in that polarity of cell enlargement is lost. Cells which would typically be elongate parallel to the vertical axis assume an isodiametric configuration, because of an abnormally large lateral expan-sion. Electron microscopic studies reveal that microtubules oriented perpendicular to the long axis of the root and located near the plasmalemma disappear from the cytoplasm during the colchicine treatment. It is suggested that these microtubules are responsible for polarity of cell enlargement in timothy roots and that their removal by colchicine permits the abnormal cell enlargement involved in "C-tumor" formation. Hauke, R. L. University of Rhode Island, Kingston-GAMETANGIA OF EQUISETUM BOGOTENSE-Spores of Equisetum bogotense were cultured and the development of the gametophytes studied. They are invariably unisexual, and their gametangia have a unique morphology. Both archegonia and antheridia become greatly exSerted, the former by extreme elongation of the neck cells, the latter by both division and elongation of the jacket cells. These gametangia appear to be a specialized derivation from the gametangia seen in E. arvense and E. fluviatile.

Rouffa, A. S. University of Illinois, Chicago Circle-AN APPENDAGELESS FORM OF PSILoTuM-An heretofore undescribed form of Psilotum was collected in 1957 at a nursery near the Shinto shrine of Ise, Japan. The aerial shoots of this form are less angular than the typical form and produce no sterile or fertile appendage!'. Shoot apices are easily visible to the naked eye since there are no appendage primordia to obscure them. The dichotomies at the distal part of the shoot may grow sympodially and occasional short branches are the result. Synangia may develop at the tips of shortened branches. The relationship of stem anatomy to growth pattern is discussed. .

Bierhorst, D. W. Cornell University, Ithaca, N.Y.-DEVELOPMENTAL ASPECTS OF THE SPORANIGATE FRUCTIFICATIONS IN SCHIZAEA AND ACTINOSTACHYS-Ontogenetically the fertile parts of leaves in Schizaea are multipinnate with a series of lateral pinnae and a terminal one. In Actinostachys, even though there may be as many as 10 fertile digits, the entire assemblage is composed of 2 lateral pinnae and a terminal one. Additional digits are the result of dichotomies which also occur to a lesser extent in Schizaea. Proximal to the growing point of the frond (or ultimate division of frond) there is a double set of marginal initials. As the pinnae are elevated as distinct morphological entities, the sets of marginal initials remain distmct over their apices. Each set of initials produces some internal tissue of the sporangiferous foliar extension. The adaxial set of initials in addition produces the flap of tissue which has been referred to as indusium. The abaxial set gives rise to the two rows of sporangial initials. In species of Schizaea and Actinostachys which have a marginal meristem in the vegetative parts, it is continuous with the abaxial set of the fertile extension.

]agels. Richard. University of Illinois, Urbana-LIGHT-AND TEMPERATURE-INDUCED MORPHOLOGICAL CHANGES IN SELAGINELLA UNCINATA-The growth and morphology of Seloqinella uncinata were observed under a range of light intensities from total darkness to 300 ft-c, and with two temperature regimes (21 C and 8 C). Although growth was halted, the morphology and subsequent photosynthetic activity were unchanged for plants consigned to 2 months of darkness. Under moderate light mtensities (200 ft-c; 12-hr day), after several months plants because completely chlorotic and died. This phenomenon was enhanced at the lower temperature. Various intermediate stages were examined for gross morphological changes and chloroplast ultrastructural differences. During early stages the leaves and stems turned a reddish-green, later pink, and finally yellowishwhite. If the plants were returned to lower light mtensities during intermediate stages in chlorosis, a regreening occurred. The ultrastructural changes in the chloroplasts followed a typical pattern of chromoplast formation: an accumulation of starch, followed by an increase in osmophilic droplets, accompanied by a breakdown of grana and intergrana lamellae. Durmg regreening this process was reversed. Infra-red gas analysis of CO2 evolution ' . and absorption by the plants demonstrated that photosaturation occurred at light intensities above those which caused chlorosis, and the compensation point was near the level at which chlorosis occurred. The results are discussed in relation to the natural habitat of the plant.

Smith, A. R. Iowa State University, Ames-AERATION TISSUE IN FERNs-A study of certain specialized structures involved in gas exchange in ferns was undertaken from an anatomical and taxonomic viewpoint. The most prominent and common of these elaborations are the so-called "aerophores" and "ventilation bands." Although apparently functioning in a manner physiologically similar to the lenticels of flowering plants, the ventilation bands are quite different anatomically. In contrast to the surrounding lavers of cells in which the parenchyma has become highly sclerotic, the cell walls of the parenchyma in the region of the ventilation bands remain relatively unthickened. A further elaboration of these ventilation bands is the occurrence of aerophores, found at the base of the pinnae or along the stipe in certain groups of ferns. They obtain their greatest size in specie'! which secrete mucilage. The aerophores, which may be up to 1 em in length, protrude through the layer of mucilage; they possess numerous stomates, and consist of highly aerenchymatous tissue. There is some correlation between taxonomic groupings and kinds of aeriferous elaborations.

Bogle, A. L. Gray Herbarium of Harvard University, Cambridge, Mass.-MAJOR FEATURES OF MORPHOLOGY AND VASCULAR ANATOMY OF THE HAMAMELI-DACEOUS GYNOECIUM-Vascular patterns in the biearpellate gynoecia of 23 of the 26 genera of Hamamelidaceae, representing all five subfamilies, have been examined. Carpels of the family contain either three (dorsal, two ventrals) or five (plus two sub-marginal laterals) prominent bundles. Among the genera progressive reduction in ovary size and ovule number (many to one) is accompanied by: increased fusion of involute carpel margins and adaxial carpel surfaces to form partially to fully septate ovaries; progressive fusion between opposing ventral and lateral bundles of adjacent fused carpel margins. Ovule traces depart from ventral bundles. Ovaries of Liquidambaroideae, Rhodoleioideae, Bucklandioideae, and Disanthoideae are half-inferior, partially septate, and pluriovulate (many to few). Each carpel is supplied with three major bundles. In Rhodoleioideae, Bucklandioideae and Disanthoideae carpel walls also receive several minor supplementary bundles, some of which anastomose with the ventral bundles. The supplementary strands may represent diffuse lateral bundles. Modifications of vasculature are introduced both through adnation between ovary and hypanthium and through fusion of flowers into heads. Ovaries of Hamamelidoideae are superior to nearly in-ferior, and septate. Each carpel bears one (minus three) ovules and is supplied by five major bundles. The ventral and lateral bundles of each margin arise separately in the receptacle but fuse near the apex of the locule to form a single marginal bundle in the style. Among the Hamamelidoideae reduction and loss of a reeeptacular stele (absent in other subfamilies) is accompanied by increasing adnation between hypanthium and ovary followed by increasing adnation of hypanthial trunk bundles with dorsal and lateral carpel bundles, resulting in a diffuse ori~n of the lateral carpel bundles from adjacent hypanthial trunk bundles in advanced cases. The trends of specialization will be illustrated and discussed.

Soetiarto, S. R., and Ernest Ball, North Carolina State University, Raleigh-ORIGIN OF PERIGYNY IN PORTULACA GRANDIFLoRA-Ontogeny of sepals through carpels occurs on the flanks of the floral apex in the manner of a hypogynous flower. During the maturation of the floral appendages, the tissues subjacent to all except the carpels undergo growth in the vertical direction by cell divisions and cell stretching, causing the attachment positions of these organs to assume the form of the edges of a bowl, at the bottom of which the carpels undergo their fusions and maturation. This perigyny is thus ontogentically late in development and may be interpreted as a derived condition. It contrasts fundamentally with the perigyny of Spiraea ulmaria as described by Gregoire, in which the bowl-shaped form of the floral apex was assumed prior to the origin of the floral appendages. Under uniform growing conditions stem length has varied by as much as 230%, shape of the leaf base has ranged from simple to crested, and root systems formed have been much stronger on some plants than on others of the same age. Difference in stem length has been related to point of origin on the parent leaf. An explanation based on differing hormonal balance is substantiated by the fact that the first plantlets to appear on attached leaves do not produce roots until those which appear later have produced numerous roots. General Section-continued genesis of these divergent leaf types; one interpretation suggests that the extensive radial growth early in foliar development of unifacial origins results from extensive divisional activity in an adaxial meristem, while the other states that unifacial leaves exhibit a sympodial growth pattern with the early radial expansion resulting from growth activity of the primary leaf apex which becomes arrested early in its development. Subsequent longitudinal growth is then interpreted to proceed from a secondary leaf apex which arises from the abaxial side of the primordium. Both types of leaf development have been described in various groups of monocotyledonous plants and have been considered as non-homologous developmental patterns. Detailed comparative analysis of early foliar development in five different populations of Acorus calamus indicates that the distinctions between these two developmental patterns are merely the results of quantitative differences in the extent of expression and time of onset of adaxial meristematic activity, as well as the distribution of growth in the derivative zones, of the shoot apex. Because both ontogenetic patterns can be found in different populations of the same species and they fall within the range of quantitative variations in the distribution and timing of growth of unifacial organs, it is suggested that these hitherto contrasting developmental patterns be considered homologous.

Anderson, E. F., and M. S. Stone. Whitman College, Walla Walla, Wa."h.-POLLEN VARIATION IN LOPHOPHORA (CACTACEAE)-Pollenof Lophophora (peyote) from its three major geographical areas was studied to determine if it would be significant in a taxonomic revision of the genus. Light-microscope analysis showed the pollen to vary in size, shape and colpae number. The southern population has grains that average 38 J.l in diam with the colpae number varying from 0-6; 3colpate grains represent more than 30% of the total. The central population has pollen averaging 41.7 J.l in diam with the colpae varying from 0-18; 3-and 6-colpate grains account for over 50% of the total. The northern population has pollen that averages 40.9 J.l in diam; there is great variation in colpae number. Inaperturate and monocolpate grains account for more than 30% but 15-colpate grains exceed 24% of the total. Only 10% are 3-colpate. Electron micrographs of the scabrate exine show that the ektexine consists of a thick foot layer with numerous columellae arising from it to support a tectum of approximately the same thickness as the foot layer. Spinules occur on the surface of the tectum. Within the middle area and often protruding through the perforate tectum is probable lipid material. The endexine is a distinct, non-stained region; sometimes a thin intine can be observed. Minor variations in exine structure were noted in the three geographical zones. Lophophora pollen morphology supports certain tentative phylogenetic and taxonomic conclusions. November, 1964 , to December, 1966 , the seasonal cycle of phloem development in P. inserta is as follows. Cambial activity (divisions) and phloem differentiation begin in early April. By the end of May, at which time xylem differentiation begins, one-third to one-half of the new phloem increment has been produced. Xylem and phloem differentiation are completed more or less simultaneously in mid-August. Cessation of function of phloem begins in mid-October with the first-formed sieve elements of the current season's phloem increment. By mid-December all sieve elements are dead and their companion cells collapsed. , 1963, and June, 1964 , indicate that in Ulmus americana the seasonal cycle of phloem development is as follows. Phloem and -xylern differentiation begin simultaneously shortly after the resumption of cambial activity in mid-April and cease simultaneously in either late July or August. With regard to a given year's phloem increment, cessation of function begins in October with the accumulation of definitive callose on the first-formed sieve elements and by mid-December only some narrow latephloem sieve elements remain alive. Most of these narrow sieve elements remain alive through winter. With the resumption of cambial activity in spring some of them develop definitive callose and collapse. Others remain alive until October and at that time are among the first sieve elements to die as the main period of cessation of function begins.

Evert, R. F., C. M. Tucker, and J. D. Davis.

AMERICAN A-An ontogenetic study of variously treated sieve-tube members by light and phase microscopy indicates that the mature sieve-tube member of Ulmus americana normally contains a tonoplast which delimits parietal layer of cytoplasm from vacuole. Dispersing slime bodies give rise to strands (0.5 J.l or less in diam) which run mostly vertically in the parietal layer of cytoplasm and which are continuous from one sieve-tube member to the next through the sieve-plate pores. Many mature sieve-tube members contained nuclei.

Evert, R. F., and B. P. Deshpande. University of Wisconsin, Madison-8LIME SUBSTANCE IN SIEVE-TUBE MEMBERS OF ULMUS AMERICANA-An ontogenetic study of sieve-tube members of Ulmus americana with the electron microscope has revealed that the substance comprising the slime bodies of very young sieve-tube members is tubular in appearance, individual tubules measuring about ISO A in diam. At this stage the slime bodies are bordered by a single layer of membranes. The origin of these membranes is uncertain; however, some of them are suggestive of dictyosome vesicles, others of endoplasmic reticulum cisternae. At the time of slimebody dispersal the slime substance appears mostly fibrillar or filamentous, individual fibrils measuring about ISO A in diam, In the mature (fully perforated) sieve-tube member the slime substance is similar to that of the dispersing slime bodies. regions. Of the total 125 cells studied in the interfascicular files consisting of fibers only, 68 cells and their derivatives divided anticlinally 1-4 times, with 1 and 2 the most common, during the production of 2.5 mm of secondary xylem. Approximately 68% of the anticlinal divisions were oblique; the remaining were lateral.· The average length of the partition in oblique anticlinal divisions was 31% of the length of the dividing initials. In interfascicular files consisting of fibers and vessel elements, there were 1-8 divisions, with 2-4 the most common, in the 38 cells followed. There were almost equal numbers of oblique and lateral divisions in these files. The average length of the partition in oblique anticlinal divisions was 37% of the length of the dividing initials. In the fascicular regions 40 cells and their derivatives underwent 1-7 anticlinal divisions, with 2 and 3 the most common. Approximately 60% of the divisions were lateral. The ratio of partition length to cell length averaged almost two-thirds in these files. The average length of the partition in lateral divisions in all files was about 50% of the length of the dividing initials. Orbigny have revealed tracheary elements which may have scalariforInly perforated end walls. The writers consider that no more than this prudent statement is in order at this moment. The tracheary elements studied are long, slender, essentially scalariform ones with long, sloping end walls. Pit membranes in the end walls are often very tenuous, and it is possible, unfortunately, that the membranes may be shattering or disintegrating during preparations. Further investigation, including experiments with India ink injections and the preparation of additional stained sections, is under way.

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3:40 Conde, L. F. Duke University, Durham, N. C.-VESSEL MEMBER DIMENSIONS IN THE CACTACEAE-Lengths and widths of the vessel members of 18 species in 14 genera of the Cactaceae were measured. When the results were plotted against the classification of Britton and Rose, vessel elements were seen to be narrower and possibly longer in the presumably more advanced members of the family, a result contrary to the usual phylogenetic trends in vessel elements. It is 'suggested that in the Cactaceae these trends are the result of adaptation to increased dryness and that ecological-anatomical studies are needed.

Calvin, C. L. Oregon College of Education, Monmouth-ANATOMY OF THE AERIAL EPIDERMIS OF THE MISTLETOE PHORADENDRON FLAVESCENs-The study is concerned with the developmental changes occurring in the aerial epidermis of a plant that retains its epidermis in more or less modified form for many years. Initial modifications of the epidermal layer include the alteration of trichomes and stomata and a concomitant increase in the thickness of the cuticle. Eventually, because of the death of epidermal cells and the activity of subepidermal layers, the integrity of the epidermal: layer may be lost.

Sattler, R.McGill University, Montreal-c-Raronr OF APROJECT ON FLORAL DEVELOPMENT-Goal of the project is to describe the floral development of approximately 50 species of angiosperms and to publish the results in the form of an atlas of floral development. So far the following species have been .studied: Monocotyledoneae-Acorus calamus L., Alisma triviale Pursh., Allium cowani Lindl. Butomus umbellatus L., Habenaria clav.ellata (Miehx.) Spreng., Juncus ejfusus L., Ruscus hypoglossum L., Scilla violacea Hutch.; Dicotyledoneae-Albizia distachya Macb., Anthriscus silvestris (L.) Hoffm., Asclepias syriaca L., Cheiranthus cheiri L., Chelidonium majus L., Convolvulus sepium L., Hibbertia scandens (Willd.) Dryand., Hydrophyllum virginianum L., Lantana camara L., Lysimachia nummularia L., Lythrum salicaria L., Malva neglecta Wallr., Myrica gale L., Pyrola elliptica Nutt., Silene cucubalus Wibel, Solanum dulcamara L., Tragopogon pratensis L. A special technique has been used to permit the direct study of the floral development in three dimensions. The material is fixed in FAA or 70% ethyl alcohol, then dissected, if necessary, and stained in a solution of acid fuchsin in 95% ethyl alcohol. For photographing the material is kept immersed in 100% ethyl alcohol. An incident-light condensor and low-power objectives with dipping cones are used besides the standard equipment. The resulting photographs show the floral apices and the primordia of the appendages. Furthermore, the protoderm cells are visible in most instances; sometimes even nuclei and/or nucleoli of these cells can be distinguished. The observed development of the flowers is considered in terms of a number of concepts such as sequence and position of primordial inception, postgenital fusion, zonal growth, equifinality, etc. The importance and relevance of the results to various botanical disciplines will be briefly discussed.

Homsher, P. J. Old Dominion College, Norfolk, Va.-GENETIC STUDIES ON A CHENOPODIUM HYBRID-Several traits were examined in the cross, C. missouriense (2n = 54) females XC. giganteum (2n = 54) males. The F1 individuals exhibit the characteristic red apex of the male parent and this trait segregates in the F 2 generation in the typical single gene pair ratio. The minimum number of genes affecting variation in apex color, leaf color and ratio of leaf length to leaf breadth was estimated, using the formula published by Charles and Goodwin (1943) . These were 12, 2 and 1, respectively. Charles and Goodwin's formula was not applicable to another trait, leaf dentation; therefore the number of genes affecting it was not determined. It is speculated that some of the genes associated with the two color traits may be common to both.

Kumler, M. L. Southern Illinois University, Edwardsville-SuCCESSION OF PLANTS NATIVE TO THE SAND DUNES OF THE OREGON COAST-The vegetation of the Oregon coast is characterized by a variety of stages of plant succession which are widely repeated throughout the sand-dune area. Parabolic sand-dune succession was studied on 48 plots within a 165-mile section of the Oregon coastline over a period of 2 years. Various sand-dune communities were described and related to their successional sequence. Both plot and plot-less techniques were used to obtain data for frequency, cover, density, and dominance. Successional stages of upland areas of coastal sand dunes are represented by nine communities of plants. These communities range from scattered pioneer, herbaceous plants to the near-climax forest tree stands. Most of the dominant species graded from one community to another within the succession. The most notable exception occurred in the herbaceous community along the protected edges of dunes.

[Vol. 55 Session 6. Tuesday Aftemoon. JOSEPH EWAN, presiding..

Berkeley, Edmund, and Dorothy S. Berkeley. Central Virginia Community College, Lynchburg-THE HISTORY OF THE NAMING OF THE LOBLOLLY BAy-COrrespondence concerning the name which should be given to this attractive tree involved several members of the 18th century international botanic fraternity for a number of years. These letters provide an interesting view of that period of the history of botany. Books especially written for children were not common until the 18th century. In the United States the early works were mostly reprinted from or modeled on English or European books. Botany was early taught in the context of moral Ieesons: later it was presented in books in which the scientific information was modified for entertainment and educational purposes. In the second half of the 19th century some well-known American botanists, for example Asa Gray, William Beal, and Liberty Hyde Bailey, wrote botanical works designed for children. Examples of the t;rpes of botany included in books before and after the initiation of writings by botan-ist~is compared. It is proposed that in their works for children the botanists distilled their science and included only those aSJ,>ects which they deemed most important. Thus children S botanies may prove to be a key to the better understanding of the history of botany.' 3:00

Stannard, Jerry University of Kansas, Lawrence-THE TRANSFORMATION OF CLASSICAL PLANT NAMES IN THE MIDDLE AGEs-Greek and Roman plant names were often modified and in some cases transformed nearly beyond recognition in medieval literature. Some of these transformations were the result of scribal carelessness and dialectal peculiarities. Others, however, were caused by a deep-seated confusion concerning the nature and identity of the 'plant whose name or names originated in classical antiquity. As a consequence error was introduced in medieval botanical literature by nomenclatural changes and w!l;s perpetuated by the li~erary forms (commentaries, glossaries, etc.) used by medieval botanical writers. In the myxomycete Didymium iridis (Ditmar) Fries vegetative or plasmodial fusion is controlled by a compatibility system consisting of several loci. On the other hand, mating capacity is determined by an i-locus multiple allelic system in which all heteroallehc crosses are fertile. The operation of this system is such that each plasmodium from heterothallic isolates typically carries a different pair of mating-type alleles. Vegetative fusions which bring together non-identical pairs of mating factors are apparently rare, probably because of dissimilarity in the plasmodial compatibility systems of the various isolates. In the laboratory appropriate interisolate crosses sometimes yield hybrids which are genetically sufficiently similar to allow for occasional production of mating type heterokaryons by means of plasmodial fusion. A heterokaryon composed of AIA2and A2A· nuclei was induced to sporulate and recovery of the 3 factors was attempted. Retrieval of A 2 and A· in a 1: 1 ratio suggests that only A2A4 nuclei survived to become incorporated in spores. In view of this, heterokaryons were produced in which there was a 4: 1 and 10: 1 size difference in favor of the AlA2 plasmodium. Even under these conditions only As and A· mating types were recovered. The broad implications of heterokaryosis and nuclear selection as they r~late to certain aspects of myxomycete life cycles will be discussed.

Collins, O. R. Wayne State University, Detroit -COMPLEMENTATION BETWEEN PLASMODIAL COLOR MU-TANTS IN A TRUE SLIME MOLD, DIDYMIUM IRIDls-The wild type color of D. iridis plasmodia is brown, but two color mutations obtained from different isolates (or strains) are now known. Each of these, when present in the doubly recessive condition, renders a plasmodium cream-colored. However, all interisolate crosses yield brown plasmodia, including those which bring together the two mutant alleles. These results are explainable on the assumption that the mutants are not deficient for the same function and are thus complementary. Analysis of a double mutant cross (b l + X + b S ) yields four classes of F I clones <++, b l +, +b s , and bibS) in approximately equal numbers, arguing a~ainst linkage. Based on more than 600 crosses, it is possible to represent cream-colored AMERICAN JOURNAL OF BOTANY [Vol. 55

Microbiological Section-continued b l + + b 2 plasmodia from the two isolates as bi +: and +: b 2 ' respectively. Since thin layer chromatography studies suggest that the chief difference between brown-and creamcolored plasmodia is that the former produces larger amounts of a red pigment than the latter, it is easy to suppose that each of the two mutations partially blocks synthesis of a red pigment at different points in the same biosynthetic pathway. The literature reveals no previous report of genetic complementation in a myxomycete.

Henney, Mary R. Lunar Receiving Laboratory, Brown and Root-Northrop, Houston, Texas-MATING-TYPE SYSTEMS IN THE MYXOMYCETES PHYSARUM GLO-BULIFERUM AND PHYSARUM BILGRAMU-Clones were established from two isolates (collections) of myxomycetes identified as Physarum globuliferum (A and B) and from one isolate identified as Physarum bilgramii. The P. bilgramii was collected as a blue plasmodium and upon fruiting the lime in the capillitium, in the stalk, and on the peridium was also blue. The clones of each isolate could be divided into two mating types characteristic of a one-locus, two-allele mating-type system. When the clones of both mating types of the two P. globuliferum isolates were mixed together, plasmodial formation occurred in all crosses indicating the existence of multiple alleles at the incompatibility locus. When clones of both mating types of the P. bilgramii were mixed with those of P. globuliferum, plasmodial formation again occurred in all crosses indicating that the incompatihility locus of P. bilgramii was allelic to the incompatibility locus of P. globulife:rum. Mass spore cultures from sporangia obtained from such crosses were viable. Although the original plasmodium and the subsequent fruiting bodies of P. bilgramii were blue, all plasmodia obtained in culture were white and the sporangia derived from these plasmodia were also white and indistinguishable from P. globuliferum. Thus far all attempts to induce the formation of the blue pigment in these plasmodia have failed. 

the four replicates. In many cases all four replicates fruited. Thirty-five backcrosses yielded var, squamulosus type fruits and 29 yieldedvar, tigrinus fruits. Fruits from replicates of the same cross were consistent for varietal type. These results strongly suggest that the difference in hymenophore morphology between the two varieties is controlled by a single pair of alleles. Sharp differences in "fruiting competence" among the various backerosses indicate a genetic basis which should be investigated further.

Robinson, A. D. University of Iowa, Iowa City-SUPRAINCOMPATIBILITY IN PANUS TIGRINUS VAR. SQUAMULosus-A number of spontaneously occurring sectors have been isolated from normal mycelium of P. tigrinus var. squamulosus. The sectors are all incompatible with the normal mycelium but show a high degree of compatibility when mated with each other. Three of the sectors which are compatible in all combinations with each other were produced by the same normal dikaryon (Ax Bx:Ay By). It appears that both the A and B incompatibility factors. of the normal mycelium have either mutated or have been modified by some mutation at another locus, since a change in only one of the incompatibility factors would not account for the origin of such a series of sectors. Basidiospores which are produced from compatible crosses of the sectors show a regular tetrapolar pattern when crossed with each other or when backcrossed to the parents. The progeny show the same incompatibility with the normal mycelium as did their parents. The fruiting structures produced by compatible combinations of sectors are nothing more than coralloid or raduloid structures a few mm high and are completely lacking a stalk or pileus. The basidia and basidiospores of the sectors have the same morphology and dimensions as the basidia and basidiospores of the normal fruits. The origin of the sectors is obscure since the strict incompatibility existing between the sectors and the normals prevents crossing experiments.

Jacobs, J. B., and Vernon Ahmadjian. Clark University, Worcester, MasS.-ULTRASTRUCTURE OF THE LICHEN ALGA Tnnaorrxrx-c-Ultraetructural studies are being conducted on lichens and the isolated lichen symbionts. The purpose of this paper is to describe one phase of this work, namely, the ultrastructure of the phycobiont Trebouxia. This genus previously has been separated into two groups with the aid of the light microscope. In group 1, which is found in fruiticose lichens, the divided chloroplast fragments assume a parietal position in the cell. In group 2, found commonly in foliose and crustose lichens, the divided chloroplast fragments retain a central position in the cell. Other differences can be found at the ultrastructural level. Group 1 Trebouxia are found to have the normal chlorococcoid pyrenoid, while group 2 species have a highly vesiculate, stellate-shaped pyrenoid with small electron-dense bodies scattered throughout. The core of the group 2 pyrenoids has a lamellar structure. The two groups differ also in their arrangement of starch granules around the pyrenoid, organization of chloroplast lamellae, and the size and distribution of mitochondria. A. peruviana is homothallic: however, the morphology of this organism is different from all other isolates identified as Anixiops1:Sand its inclusion in this genus is questionable. Forty isolates of organisms identified as belonging to the genus Anixiopeis are under study. Single ascospore isolations indicate that 20 of these isolates are homothallic and 20 are heterothallic, Clones established from each of the heterothallic isolates were crossed among themselves. The results of these crosses show the existence of a singlelocus, two-allele mating type system in all 20 heterothallic isolates. When clones from the individual isolates were crossed to clones from the other isolates, the results indicated the existence of at least four different genetic groups. Studies are being conducted that show morphological differences also exist that correspond to the genetic groups. Morphological studies of the homothallic isolates are also being conducted. 'Red Kidney' to simazine (2 chloro-4, 6-bis ethylamino-S-triazine) and kinetin was tested. The plants were analyzed with respect to the length of the leaves and stems, the number of flowers, and the number and size of nodules. A three-factorial analysis was performed combining the herbicide at 5 X 10-5 M and 5 X 10-6 M, kinetin at 9 X 10-7 and 9 X 10-8 M, and the presence and absence of Rhizobium phaseoli in all possible combinations. At both concentrations of simazine, nodulation was inhibited. However, at either kinetin concentration formation of nodules was evident. The actual mechanism of induction is unknown. A comparison was made between groups which were simultaneously treated with kinetin, simazine, and an inoculum of Rhizobium phaseoli ATCC 14482. The nodules formed by species of Rhizobium are different from the pseudonodules induced in tobacco roots. Simazine (5 X 10-6 M) caused chlorosis in plants. Chlorosis was also observed 2-3 weeks later with 5~X 10-6 !f simazine with the action site being the mesophyll areas of the leaf. No antagonistic effects were observed with application of kinetin. parasitic on an unidentified myrtaceous leaf. A comparison at Beltsville of the Indian material with the type of Phaeofabrea miconiae Rehm, until now known only from four collections from Brazil and Venezuela, proved the two to be identical. There are two additional species in the genus: P. lachnoides (Rehm) Sydow from Brazil and Costa Rica and P. leonensis Sydow from Sierra Leone. All Phaeofabrea spp. are hyperparasites of Phyllachoraceae, a family of stromatic pyrenomycetes. Contrary to the previous published accounts, the ascospores of P. miconiae are unseptate. The "septum" of these authors is a hyaline cytoplasmic band in the equatorial region of the otherwise brown ascospore. As the ascospore matures an inner secondary wall is deposited except in this equatorial region. The pigmentation in the primary wall also becomes denser, making it somewhat more conspicuous than the inner wall. The hyaline band in the ascospore is also characteristic of the other two species of Phaeofobrea, PALEOBOTANICAL SECTION [Vol. 55 Session 7. Tuesday Afternoon. C. B. BECK, presiding.

Taylor, T. N. University of Illinois, Chicago Circle-THE SCANNING ELECTRON MICROSCOPE, A NEW RESEARCH TOOL IN PALEOBOTANy-The development of the scanning electron microscope (SEM) provides a new method of examination and interpretation of surface features of plant microfossils and microdetails of macrofossils. Its availability reduces limitations of resolution, depth of field, and maximum magnifications available imposed by light microscopy. Transmission electron microscopes provide greater depth of field, higher magnifications and resolution than light microscopes, but are limited because of the necessity of using thin specimens or vapor-deposited replicas of specimen surfaces. The scanning electron microscope combines advantages of both light and transmission electron microscopes and is particularly adapted to the examination of solid specimens having minute surface features. In addition, the twoaxis rotational capability of the specimen stage of the scanning electron microscope allows one specimen to be viewed and photographed at several different angles. Magnifications from 14 to 100,000 times are available, with the depth of field being 500 times that of the light microscope. Scanning electron microscopy depends upon the collection of secondary electrons which are emitted from the surface upon the impingement of higher energy primary electrons. Voltages range from 1.5 kv to 20 kv, thus making it possible to investigate materials which would be destroyed by the 50 kv, or higher, voltages of conventional electron microscopes. A further significant feature is the possibility of preparing stereopictures. Several Carboniferous small-spore genera are illustrated and applications of the scanning electron microscope to paleobotanical studies are discussed.

Traverse, Alfred. The Pennsylvania State University, University Park-WHAT IS SPOROPOLLENIN?-Bulk samples of chenopodiaceous pollen (Beta vulgaris L.) have been treated with various organic solvents, acids and bases to remove all but the ultra-resistant exine "skeletal" material. This artificially "refined" substance is presumably equivalent to the naturally occuring material that makes up the exines of fossil pollen and (embryophy:te) spores-"sporopollenin." Elemental analysis, hydrolysis 'products, and Infrared absorption spectra analysis show the 'subetance to be a carbohydrate, a polysaccharide of high molecular weight. This is contrary to some previous statements in the literature which attribute the resistant nature of sporopollenin to terpene, wax or lipid constitution. The units in the chains are thought to be similar to those of glucuronic acid. Like fossil sporopollenin, that separated from modern pollen is very sensitive to oxidation. Treatment with H 202 solutions quickly breaks down beet-pollen exines that had withstood weeks of attack by hot mineral acids and bases. The extraordinary resistance of beet-pollen exines to degradation possibly accounts for the abundance of fossil chenopod pollen in various sediments. Ohio) . The distribution of lignin as indicated qualitatively by its blue fluorescence in intact tracheids of the Pleistocene specimens investi-gated here is similar to that of comparable extant specimens. The trilamellar organization of the cellulosic component of the secondary wall of traeheids is remarkably preserved in the hardwood specimen in Griffin Hill peat and in Cedrus penhallowii. In compression-wood tracheids of Two Creeks Picea in which some of the inner lamellae of the S2 wall layer are degraded, it is reported that in the remaining lamellae of this wall layer the cellulosic component persists in the birefringent state. This suggests thnt disorganization of the S2 wall layer, at least in this specimen, follows a course from lamella to lamella from the lumen side outward, and not simultaneously through the wall layer as a whole. An embedding technique is described which makes practicable the microtomy of fossil woods and other paleobotanical materials for structural studies in the transmitted-light microscope. The method appears to be applicable to specimens in which organic continuity can be maintained during processing for embedment.

Drum, R. W. University of Massachusetts, Amherst-IN VITRO SILICEOUS PETRIFACTION OF PLANT TISSUE-Plant tissue can be petrified by impregnation with natural waters of high dissolved silicate content. This process is easily duplicated in the laboratory by immersing fresh plant tissue in saturated sodium metasilicate solutions. The silicate impregnates the intraand inter-cellular spaces where it deposits as opaline silica on exposed cell-wall surfaces. Stable replication of these spaces requires 12-24 hr at room temperature and about one-half that time over a steam bath. Entire impregnated pieces are not preserved intact but fragment into single cell silica replicas and macroscopic cell aggregates, when the organic material is removed by wet ashing with a mixture of chromic and nitric acids. Carbon replication of the silica replicas permits electron microscopic examination. Intercellular connections such as paired pits. simple or bordered, and the surface configuration of wall fibril orientation are well preserved. In vitro siliceous petrifaction of alleged modern allies of extinct or fossilized plants might enable us to interpret more accurately the microstructure observed in plant fossils.

Schopf, J. W. University of California, Los AngeleS-PRECAMBRIAN MICROORGANISMS FROM CENTRAL AND SOUTH AUSTRALIA-8tromatolitic black cherts from the Late Precambrian Bitter Springs Formation of the central Australian Amadeus Basin contain a diverse assemblage of exceptionally well-preserved filamentous and spheroidal plant microfossils. Some 30 species of green and bluegreen algae, bacteria, probable fungi and other microorganisms are indigenous to this approximately 1,000million-year-old deposit. Certain of the spheroidal green algae of the assemblage contain structures interpreted as representing partially degraded nuclei; these chlorococcoid algae appear to be the oldest eucaryotic organisms now known. Although many of the microorganisms are rather dissimilar from modern thallophytes, several of the Bitter Springs algae are comparable in morphological detail to extant Cyanophytes, In particular, microorganisms resembling members of the following genera are represented: Lyngbya, Oscillatoria, Microcoleus, Spirulina, Anacystis, and perhaps Anabaenopsis. On the basis of lithologic similarity and stratigraphic position, the Bitter Springs Formation has been correlated with the Late Precambrian Skillogalee Dolomite of the Adelaide Geosyncline. Septate, apparently heterocystous algal filaments, spheroidal algal unicells, and a distinctive ascus-like microfossil of uncertain systematic position have been detected in cherty units of this South Australian formation. Although the Skillogalee filaments appear to be conspecific with one of the Bitter Springs blue-green algae, the evolutionary conservatism exhibited by the Bitter Springs cyanophytes indicates that these organisms are probably unreliable "index fossils"; the occurrence of this alga in both deposits is not necessarily indicative of temporal equivalence. These two Australian assemblages of organically and structurally preserved microorganisms provide additional links in the rapidly expanding knowledge of Late Precambrian organisms and their evolutionary status.

Recess.

3:30 Dennis, R. L. University of Iowa, Iowa City-FOSSIL FUNGAL MYCE:(,IUM WITH CLAMP CONNECTIONS FROM THE MIDDLE PENNSYLVANIAN-A fungal mycelium which bears chlamydospores and clamp connections has been found within the wood of the coenopterid fern, Zygopteris illinoiensis, which is preserved in a coal-ball petrifaction of Middle Pennsylvanian age. The presence of clamp connections is a structural characteristic occurring at present only in the class Basidiomycetes. This structure, which insures that sister nuclei from a conjugate division of a dikaryon become properly separated into daughter cells, is an integral part of the basidiomycete life cycle. The occurrence of clamps is direct evidence of the existence of the dikaryotic stage in the life cycle of the Basidiomycetes, and as such supports the premise that the characteristic life cycle of the Basidiomycetes was probably evolved to a point comparable to that of modern fOrIDS by the middle of the Pennsylvanian Period. This provides the first indisputable evidence of the presence of Basidiomycetes in the Paleozoic.

Andrews, Henry, Andrew Kasper, and Patricia Gabbey. University of Connecticut, Storrs-EARLY DEVONIAN PLANTS FROM NORTHERN MAINE-During the past 3 years fossil plants that are of Lower Devonian or lower Middle Devonian age have been found at several localities in northern Maine. One of these was recently described under the new binomial Psiwphyton forbesii. Two other spineless plants are probably referable to Psiwphyton: (1) A small, dichotomously forking plant with axes up .to about 2 mm in diam; the specimens are abundantly fertile and bear numerous paired sporangia at the tips of the ultimate branchlets, (2) A somewhat larger plant of monopodial habit with axes up to 3 mm in diam; this occurs in great abundance through several inches of rock at one locality, but sporangia have not been observed. One of the most interesting members of the flora is a rather stoutly spiny plant exhibiting Il-branching and with laterally-arranged sporangia about 6 mm in diam. The general habit resembles that of Zosterophyllttm except that it is spiny and the sporangia are borne on conspicuous stalks. A Taeniocrada-like plant, Psilophuton. princeps, and several other spiny types are included in the flora.

Matten, L. C. Southern Illinois University, Carbondale-A lIDDLE DEVONIAN FLORA FROM NEW YORK-A large number of plant petrifactions was collected from a Middle Devonian locality near Cairo, N. Y. The fossils were found in a black shale lens in rocks equivalent to the Hamilton group, Erian stage (Givetian). In addition to the plants, fish scales and plates, and branchiopods were present in the matrix. A preliIninary survey showed the flora to include: ActinoxyltJn, Cladoxylon, Reimannia, Stenokoleos,and a number of new plants. The axes of the new plants were protostelic with mesarch primary xylem. Many specimens had three fluted protosteles. The variable shapes of the steles created a problem in deterInining parameters of species. One group of axes seemed to be referable to Aneurophytonj however, pinnule traces were present. Terete axes with terete, mesarch protosteles were common. Two specimens are of a plant with abundant secondary xylem and several vascular strands in the base of an appendage. Lycopods are absent from the flora.

Sebby, W. S., and L. C. Matten. Southern Illinois University, Carbondale-THE IDENTITY OF AR-NOLDELLA AND KALYMMA-ReexaInination of the type specimen of Arnoldella minuta revealed the following features not noted in the original description: a singlelayered epidermis of rectangular cells; outer region of cortex consisting of circumferentially alternating bands of sclerenchyma and parenchyma; tracheids with scalariform thickenings; and a lateral appendage supplied by a single mesarch trace that was terete in cross section. A second specimen of Arnoldella minuta was found at the type locality in Junction City, Ky. The new specimen showed several additional features: the adaxial surface of the axis had a longitudinal groove and was slightly flattened; the concave surface of the C-shaped xylem strand was adaxial; the lysigenous areas were sacs and not canals; and the sclerenchyma strands of the outer cortex anastomosed. The features that supported the identity of Arnoldella and Kalymma were: xylem bundles either separate or showing extensive lateral fusion; presence of a sparganum cortex and uniform groundmass parenchyma; mesarch maturation pattern and scalariform tracheida; and xylem in a C-shaped configuration. 

America. Two principal species are recognized: S. radiatus present from Visean to Westphalian Band S. gracilis from Westphalian C to Stephanian A. A definite transitional gradient in size and morphological characters exists, with significant changes occurring at the Mississippian-Pennsylvanian boundary (Namurian A to B) and from Westphalian B to C. The ability to view this continuous stratigraphic sequence reveals the difficulty in confident demarcation of species. An emendation of the genus is also presented.

Clendening, J. A., and P. W. Nygreen has yielded numerous specimens of a distinctive. new spore genus. The spores are monolete, oval in outline, and range from about 100 to 135,.. in overall length. The exine has distinct separation of its layers and the ektexine is sculptured with conspicuous spinae. The monolete suture exhibits angular deviation near its center, as in Schopfipollenites Potonie and Kremp (1954) which is an associated constituent of the small-spore assemblage. The general morphological features of the new spore indicate a probable relationship to the Medullosaceae, a family of Paleozoic pteridosperms. Stigmaria, anatomically distinct from the well-known S. ficoides, has been found in coal balls from the Upper Pennsylvanian of Illinois. The new species is characterized by having a dissected siphonostele with a central parenchymatous pith. The exact outline of primary xylem cannot be determined and no direction of differentiation can be recognized at present. Apparently the primary and certainly the secondary xylem are dissected by gaps associated with the departure of vascular traces to lateral appendages (rootlets). These gaps appear ovate to orbicular in tangential sections of the secondary xylem which is predominantly multiseriate. Both primary and secondary cortical tissues are present. The primary cortical tissues are typical of those of other forms of Stigmaria; however, the secondary cortical tissues are almost identical with those known to have been produced in aerial stems of Sigillaria. The deeper secondary cortex appears to have been produced by one or more meristematic zones at the inner margin. An alternative method of designating cortical zones which does not imply a comparison of secondary cortex of lycopods with the periderm of seed plants is presented. Lateral appendages or rootlets, borne in a spiral arrangement on the axis, are characterized by having a monarch collateral bundle suspended in the hollow middle cortex of the appendage by a parenchymatous connective for the entire length of the free appendage. The parenchyma bridge and outer cortex of the appendage contain a branched system of tracheids in connection with the xylem of the appendage bundle. Abscission of the lateral appendages occurs, and the abscission zone produced has a distinct and consistent histology and configuration. The new species forms a well-defined anatomical type which may be distinguished from Stigmaria ficoides on the basis of features of the primary xylem, secondary xylem, primary and secondary cortical tissues, and the histology and mode of abscission of the lateral appendages. 

FLOATs-Azolla montana is described as a species having numerous very inconspicuous floats. These number from 10-20, occur in 2-3 tiers and are scarcely to be distinguished from the columella of the swimming apparatus to which they are attached. The columella is hollow, thimble-like, and covered with hairs like those of the perispore around the megaspore. Similarities between floats and columella suggest a phyletic origin of the former from the latter.

Frankenberg, J. M. University of Illinois, Urbana-ABscISSION OF LATERAL APPENDAGES OF STIG-MARIA-A process resembling foliar abscission has been found to occur in the stigmarian systems of Lepidodendraceae and Sigillariaceae; by means of it the lateral appendages or rootlets became functionally cut off from the appendage-bearing axis. This abscission corresponds closely with typical foliar abscission in deciduous seed plants. Differences in the configuration of the abscission zone occur in the stigmarian systems of Lepidodendraceae and Sigillariaceae. These differences may be correlated with features found in cast specimens.

Recess. 10:15 similar to those found by Pocock (1962 ), by Singh (1964 in the McMurray Formation of the Canadian plains, and in the Patuxent-Arundel of Maryland (Brenner, 1963) . Dicots are represented in the overlying Fall River.Formation by a few small, prolate, tricolpate pollen with reticulate to smooth sculpture. These pollen species are most like ones found by Brenner in the oldest portion of the Patapsco Formation of Maryland (probably early Albian). The pollen record indicates that during Fall River time conifers were the dominant forms; ferns were abundant but did not produce as diverse spore types as in the Lakota.

Eyde, R. H., and E. S. Barghoorn. Smithsonian Institution, Washington, D.C., and Harvard University, Cambridge, Mass.c-Fossn, RECORD OF ALANGIACEAE-The living Alangiaceae, all usually assigned to Alangium, comprise about 20 species of trees and shrubs confined to Asia, Africa, and islands of the Pacific and Indian Oceans. Fossils attributed to the family have been collected often in Europe, more rarely in North America. Although there are some reports from Cretaceous and Pleistocene horizons, the most interesting finds are of Tertiary age; these include leaf remains, pollen, and fruits. The identity of most of the leaves has been questioned, but a high proportion of the fruits and associated pollen undoubtedly belong to Alangium. Fruits from brown coals, whatever their age or geographical source (Japan, Europe, Vermont), usually resemble fruits of A. platanifolium, a modern species of China and Japan. This is puzzling because A. platanifolium appears to be one of the most recently evolved members of its section (sect. Marlea).

Dilcher, D. L. Indiana University, Bloomington-REvISION OF EOCENE PALMS FROM SOUTHEASTERN NORTH AMERICA BASED UPON CUTICULAR ANALYSIS-Incomplete fragments of palm foliage have always presented a problem to paleobotanists. It is very difficult, if not impossible, to give a meaningful generic determination of such fragmentary fossil material. Only by a comparison of the arrangement of the venation of such fossil fragments with the venation of more completely preserved specimens have attempts been made to use such fragmentary material. However, since the parallel venation of the lamina of palms is often not unique to any particular genus, the determinations based upon venation of leaf fragments is generally not satisfactory. Several fragments of palm leaves and a few nearly complete leaves have been collected from Eocene deposits of western Tennessee. Most of this fossil material has good cuticle preservation and the leaf fragments can be easily related by cuticular analysis to the more complete leaves which have been found. On the basis of venation and gross morphology, the palm leaves and leaf fragments studied can be identified as either Chamaedorea danai or Sabalites grayanus which Berry (1916, 1930) recognized in these deposits. However an investigation of the cuticular material indicates that there are three types of fossil palms present. The similarities of these fossil leaves and their cuticular features to modern palms indicates that two of these fossil palm types have close affinities with the Sabiloid palms and one fossil palm type has affinities with the Chamaedoroid palms.

Cross, A. T. Michigan State University, East Lansing-THE SOURCE OF PALYNOMORPHS IN THE GULF OF CALIFORNIA-Distribution of palynomorphs in the Gulf of California is much more complex than was anticipated at the beginning of the study. Classic postulations of relatively constant diminution seaward of landderived palynomorphs are extensively modified in such a basin. The reconstruction of any reasonable picture of the character of vegetation and plant-community organization in areas surrounding such a sedimentary depo-sitional area on the basis of distribution ot spores and pollen is not possible, because whole plant communities containing a wide variety of plants, as well as many individual species from partially represented communities, are not represented or are only sparsely represented. The causes of the disproportionate representation of palynomorphs are many, but some of the more significant are: (1) wind pollination vs. insect pollination (wind pollination is virtually a prerequisite for distribution at any distance from the parent plant, even though water may be equally or more important as an agency of transportation); (2) the durability factor, i.e., the differential degree or rate of degradation and destruction of palynomorphs (this is extremely variable for different species and even for whole groups of plants); (3) energy conditions both in transportation and at depositional sites and periodicity of effective movement by transporting media (such energy peaks or maxima as storms, tidal waves, seasonal winds and floods have much greater effect than 'average" conditions); and (4) re-cycling of sediments. Some palynomorphs show high concentrations coincident with distribution of clays, at delta mouths, and in the vicinity of or in front of submarine channels. Low concentrations occur along some shores because of dilution by terrigenous sediments (rate of sedimentation), winnowing and penecontemporaneous re-cycling (affected by energy conditions, geomorphology of the basin, ete.). Some palynomorphs decrease in percentage offshore and others show increase in relative percentages (the result of greater durability and inherent hydrodynamic or aerodynamic properties); none show increase in absolute frequency beyond the shelves. Session 7. Wednesday Afternoon. C. B. BECK, presiding.

Darrah, W. C. Gettysburg College, Gettysburg, Pa.-THE PTERIDOSPERM GENUS LESCUROPTERIS: CHAR-ACTERISTICS, DISTRIBUTION AND SIGNIFICANCE-Lescuropteris, a late Pennsylvanian pteridosperm, includes one well-defined species, L. moorii (Lesq.), and two inadequately known forms, L. adiantites (Lesq.) and L. rugosum (Lesq.) comb. nov. Lescuropteris moorii is a useful index of upper Conemaugh and lower Monongahela equivalents in the Appalachian and mid-continent regions. Lescuropteris moorii bears small seeds adaxially upon ordinary pinnules. These seeds, superficially bilateral, have a radially symmetrical endocarp, broad at the base, ovoid but bluntly tapered at the apex. The endocarp is attached by a pronounced circular pad or pedicel. Similarities to the seed-bearing Emplectopteris triangularis Halle are discussed.

Delevoryas, T., and T. N. Taylor. Yale University, New Haven, Conn., and University of Illinois, Chicago Circle--A PROBABLE PTERIDOSPERM WITH ER-EMOPTERID FOLIAGE FROM THE ALLEGHENY GROUP OF NORTHERN PENNSYLVANIA-Compressed foliage most comparable to Eremopteris zamioides occurs in shale associated with coal in the Allegheny Group in northern ,Pennsylvania. Samaropsid seeds occur in association with great abundance. Small! apparently microsporangiate organs also occur in association. Althoagh close proximity of disconnected plant parts as fossils is not evidence in itself that these plant parts were originally connected, it is, tempting to believe that such may have been the case with these leaves, seeds, and mierosporangia. Furthermore, there have been a number of previous reports with remarks about the same kind of association of samaropsi~ [Vol. 55 Paleobotanical Section-continued seeds with Eremopteris. Additional frondlike structures with the same basic pattern of construction as the vegetative eremopterid leaves have been found and offer information concerning the possible mode of attachment of the fertile organs.

Taylor, T. N., and D. A. Eggert. University of Illinois, Chicago Circle, and University of Iowa, Iowa City-A NEW PTERIDOSPERM SEED FROM THE UPPER PENNSYLVANIAN OF ILLINOIs-Recent coal-ball collections from Upper Pennsylvanian (McLeansboro)-age deposits in Illinois have resulted in the discovery of a large number of seed specimens of a new type. The radially symmetrical seeds measure approximately 7.0 mm long and 5.0 mm in diam at the broadest region between chalaza and apex. Commissured ribs are pronounced near the apex and progressively less distinct toward the base; secondary ribs are apparent only in the distal regions. The integument is heterogeneous but appears to lack a definite endotesta. The inner portion of the sclerotesta consists of exceptionally large cells that in section view give the inner surface of the integument a highly ornamented appearance. The nucellus is attached to the integument only at the base and contains vascular tissue. In its organization the new seed appears most similar to Pachytesta pusilla.

Eggert, D. A., and T. N. Taylor. University of Iowa, Iowa City, and University of Illinois, Chicago Circle-A TELANGIUM-LIKE POLLEN ORGAN FROM TIlE UPPER MISSISSIPPIAN OF ARKANSAs-Fertile frond remains apparently referable to the genus Telangium Benson have been collected from a shale unit occurring within the Wedington sandstone, Fayetteville Formation, Chester Series. The age of the material is Upper Mississippian. Although known from numerous localities in Europe, fertile remains of the Telangium type are relatively rare in North America. Relatively extensive specimens allow adequate characterization of the fertile portions of the Arkansas material. A basal axis bears primary laterals alternately. These primary laterals bear secondary laterals in a similar manner. The secondary laterals bear numerous dichotomously ramifying branchlets each of which is terminated by a synangiate pollen organ. The fertile frond region is entirely lacking any planated foliar structures. Individual synangia consist of five or six somewhat spreading pollen sacs united only at their extreme bases. The synangia measure ca. 1 mm in length and 0.8 rom in width. The individual pollen sacs are radially disposed in the cluster and have a somewhat triangular outline in transverse section. In longitudinal section the pollen sacs exhibit a rather sharply pointed apex. Spores recovered from the sporangia are radial, trilete, and range in diam from 47 to 54 p.. The walls of the grains are often folded and have levigate-to-granulose ornamentation. In the dispersed condition the pollen would be assigned to the genus Punctatisporites (Ibrahim) Potonie and Kremp. Usage of the generic name Telangium for the present material and similar compression material as well as petrifactions is discussed.

Eggert, D. A., and R. W. Kryder. University of Iowa, Iowa City-A NEW SPECIES OF THE PTERIDOSPERM POLI,EN ORGAN GENUS AULACOTHECA-A new species of thl(lpresumed medullosan pteridospermpollen organ genus Aulacotheca Halle has recently been collected from a clay pit near Redfield, Iowa, in strata of the Cherokee Group, Des Moines Series. The material is of Middle Pennsylvanian age. The most extensive specimen consists of a frond (or frond portion) lacking any planated foliar structures. Primary laterals borne alternately along the basal-most axis bear groups of stalked synangia. The exact number of synangia per cluster cannot be determined adequately. The clusters of synangia appear to be disposed all around the primary lateral axes, suggesting that the fertile portion of the frond was not planated and probably had a "bushy" appearance in life. Individual synangia measure ca. 5 mm in length and 1.5 in maximum width and consist of three or four elongate pollen masses and an extremely poorly preserved layer of thin-walled cells apparently representing sporangial wall. Pollen grains are tightly appressed within the pollen masses suggesting that the synangia were immature when fossilized. It has not been possible to determine whether the individual synangia were hollow in the central region as Halle inferred was the case in A. elonqaia, a supposition which has not been confirmed for any other species of the genus. Pollen grains of the Iowa material average 135 X 81 p.; they are monosulcate and similar to those of previously described species of this genus and numerous other genera of pollen organs of presumed medullosan affinities. The distinctness of the genus Aulacotheca is discussed.

Recess.

Schopf,]. M. U. S. Geological Survey, Columbus, Ohio-REINTERPRETATION OF THE GLOSSOPTERID SPORO-PHYLL-8ince 1952 when Dr. Edna Plumstead demonstrated fertile structures connected with foliage of the Glossopteris-type, it has been evident that the glossopterids are not allied with ferns. Only seed plants have fertile structures of this complexity, but the anatomy of the fertile structures is unknown and their external morphology is still subject to divergent interpretation. Mrs. Plumstead believed them to be bisexual, but this now seems doubtful; she postulated ontogenetic stages that must be reevaluated. The new morphologic interpretation is based on study of additional material. Probably all glossopterid fructifications are unisexual. They consist of a fleshy, dorsiventrally flattened, capitulate head (sporophyll?) mounted on a stalk which, in its proximal portion, is adnate to a leafy bract. Except for a much greater resemblance of subtending bracts to foliage leaves, this arrangement is most comparable to the bract and axillary fertile shoot of cordaitaleans, Nevertheless, a great phyletic gap separates the glossopterids from the cordaitaleans, The glossopterids probably constitute a separate and rather isolated order, a precocious and specialized group, among the ancient coniferophytes. Comparison with other groups of Paleozoic seed plants shows that in most respects the Glossopteridales are advanced and specialized. Among coniferophytes, their net-veined foliage is not as advanced as that of modern Gnetum, and it seems unlikely that the glossopterids bear any more relationship to modern flowering plants than Gnetum. Variations on the theme of dichotomous reticulate nervation have been duplicated many times in the evolution of leaves in terrestrial vegetation. Jurassic from the Mixteca Alta in Oaxaca, Mexico, yield an abundance of foliage that most closely resembles the Late Paleozoic genus Glossopteris. Associated fossils, namely cycadophytic foliage and ferns, are not characteristic Gondwanaland forms, however. If the Mexican leaves are truly Glossopteris, then the geographic and geologic ranges of the genus are considerably extended. Although morphologically indistinguishable from Permian glossopterids, these leaves might be best viewed as biologically . distinct from the Paleozoic forms. This situation, along with the fact that there are a number of kinds of glossopterid fructifications, suggests that Glossopteris is only a form genus.

Dilcher, D. L. Indiana University, Bloomington -SEQUOIA, AN ELEMENT OF THE EOCENE FLORA IN SOUTHEASTERN NORTH AMERICA-A reinvestigation of the lower Eocene flora from the southeastern states described by E. W. Berry in 1916 and revised by him in 1930 has been undertaken. This reinvestigation focuses particular attention on the fine venation and the frequently preserved cuticular material of these fossils in addition to the more general diagnostic leaf characters used by Berry. Additional fossil material has been collected from the western Tennessee Eocene clay deposits which Berry studied. A preliminary survey of this material indicates that several revisions should be made concerning the affinities of these fossil leaves with modern taxa. Leafy shoots of gymnospermous material similar to the fossils identified by Berry as Taxodium dubium and Taxites ? sp, were studied in this investigation. The leaves of the fossil material are attached to the axis spirally which is characteristic of Taxus, Taxodium and Sequoia. Because these three genera all have spiral leaves which are arranged distichously on the shoots it is often somewhat difficult to determine if compressed leafy shoots are most similar to Taxodium, Taxus, or Sequoia. However, the epidermal features of these genera are quite characteristic. The papillate epidermal cells of Taxus differ conspicuously from the non-papillate epidermal cells of Taxodium and Sequoia and the irregular transverse arrangement of the stomata of Taxodium is quite different from the longitudinally oriented stomata of Sequoia. The fossil material has cuticle preserved which was used in this study. The disposition of the stomata on the upper and lower epidermis, the nature of the epidermal cells and the accessory cells, and the longitudinal orientation of the stomata of the fossil material is nearly identical to that found in modern Sequoia semperuirens. The leafy shoots of Sequoia sempernirens commonly have smaller basal leaves and a terminal bud. Several of the fossil leafy shoots also show these characters. Therefore, on the basis of observations of the gross morphological and cuticular characters it is suggested that Sequoia was present in southeastern North America during the Eocene.

Ganders, F. R., and A. A. Cridland. Washington State University, Pullman-LEAF CUTICLES OF MIOCENE T AXODIUM DUBIUM FROM CENTRAL WASHINGTON -Leaf epidermal cell patterns from cuticles of living species of Taxodium are compared with those of Miocene T. dubium (Sternberg) Heer, collected near Rock Island, Wash. The cuticle of T. dubium provides conclusive evidence that it is specifically distinct from living species and suggests that it was likely the ancestor of T. mucronaium Ten. as well as of T. distlchum (L.) Rich., with which it has usually been compared. Leaf cuticles offer a feasible way to trace the evolutionary history of the genus Taxodium with some precision, though lack of a biosystematic study of the living species hinders interpretation. have a maximum diam of 2.5 em. Numerous scales are arranged spirally around the axis and each scale bears two winged seeds. The bract sub tending the ovuliferous scale is 3 mm long and is free from the scale throughout its length. The pith and cortex of the axis are constructed of thick-walled parenchyma cells and 18-21 resin ducts occur in the cortex. Those resin ducts entering the base of the cone scale are restricted to the abaxial side with vascular tissues occupying the adaxial side. At the tip of the cone scale is a broadly rhomboidal apophysis with a raised umbo that terminates in a stout spine. The shape of the cone, its anatomical features, and the morphology of the tip of the cone scale indicate closest affinity with the section Pseudosirobue of the subgenus Diploxylon. This is the first sp'ecies of structurally preserved pinaceous cones to be described from the Tertiary of North America, and these fossils indicate that cone structure characteristic of recent members of the subgenus Diploxylon had evolved by the Lower Oligocene. TRACHEID CELL WALLS-In many physiological investigations of ion uptake and water transport there is the assumption that available free space exists in the plant cell wall; however, there are no estimates or measurements of the actual amount of free space within the cell wall. In addition the amount of wall material itself, i.e., the cell-wall density, is an important parameter, particularly with respect to the mechanical strength of cells. Combining two-wavelength microspectrophotometry and interference microscopy, methods were developed to determine the amount of free space and cell wall density. The microspectrophotometric procedure requires the introduction of a chromophore and techniques were developed using the periodic acid-Schiff reaction. Validation of the method including hydrolysis times, staining schedules, Lambert's law tests, effects of vacuum desiccation and compression are presented, and preliminary measurements of the free space in tracheid cell walls of Pinus resinosa Ait. are tabulated.

Greenwood, M. S. Yale University, New Haven, Conn.-RooT REGENERATION: THE PHYSIOLOGY OF A POLAR MORPHOGENETIC PHENOMENON-The physiology of root formation by hypocotyl slices from dormant, mature Pinus lambertiana Doug!. embryos grown in vitro in inverted culture on Knop's medium is being investigated. Emphasis is placed on the movement and metabolism of sucrose and IAA in the section. When the embryonic root is removed by a slanting cut, the root always forms at the tip of the slanting cut, suggesting the accumulation of morphogenetic materials there. Polar auxin movement is demonstrable in the sections. On 2% sucrose medium, 10-6 M IAA promotes the number of sections producing roots as well as the number of roots per section. More than twice as much auxin is transported by sections pretreajedby IAA than by those grown on 2% sucrose alone: When the sucrose level in the medium is raised to 10%, IAA does not promote regeneration. Sections grown on high sucrose produce more roots than those on low sucrose. Thus high sucrose (10%) or low sucrose (2%) + 10-6 M IAA both promote rooting when compared to 2% sucrose alone. An interaction between sucrose, IAA, and root formation is suggested and is being investigated.

Shih, C. Y., and H. B. Currier. University of California, Davis-FINE STRUCTURE OF PHLOEM CELLS IN RELATION TO TRANSLOCATION-In EM studies of cotton seedling hypocotyl, plasmodesmata were found connecting parenchyma-parenchyma, parenchyma-companion cells, and companion cells-sieve elements. Their absence between parenchyma cells and sieve elements may point to a more specific role of companion cells in sieve-tube functioning then has been believed. In mature sieve elements callose was always present on sieve plants even with the most rapid killing-fixation possible. There was a slight increase in callose during routine fixation in cold glutaraldehyde followed by OsO,. Extra callose promoted by heating an intact stem segment 1.5 min at 45 C constricted sieve pores almost completely. Constriction of plasmodesmata in lateral sieve areas also was evident. Compression of fibrils present in sieve pores constitutes a part of the blocking mechanism. Fine structure analysis of the blocking mechanism clarifies and is 'n accord with evidence obtained by tracer studies and UV microscopy.

Peterson, Carol A., and H. B. Currier. University of California, Davis-BIDIRECTIONAL TRANS-LOCATION OF K-FLUORESCEIN IN THE PHLOEM-When K-fluorescein (0.1%) was taken up through lightly scraped areas on the leaves or stems of Vicia [oba, it was found to be translocated exclusively in the phloem. The youngest fully expanded leaves exported the dye into the stem where it moved in both directions, some entering the root system and some entering immature leaves. Mature leaves were bypassed. The same pattern of translocation .was also found using CU-assimilate as a tracer, indicating similar transport behavior for the two tracers. A study of the vascular system of V. [oba revealed that. the bundles usually do not divide or anastomose in the internodes. Fluorescein applied to the middle of the internode below the youngest fully expanded leaf was found both above and below the site of dye entry. After a short treatment time, the dye was present in different bundles in each area, indicating that movement within a bundle occurred only in one direction. After a longer time interval which allowed a lateral movement of fluorescein at the nodes, the dye could be observed in the same bundle both above and below the treated area in a number of cases. These results were confirmed by treating stems of Phaseolus vulgaris, Pelargonium sp., and Vinca rosea, and petioles of Ecballium elaterium. It is concluded that individual sieve tubes as well as bundles conduct unidirectionally.

Schmid, W. E. Southern Illinois University, Carbondale-ON THE EFFECTS OF DMSO IN CATION TRANSPORT BY EXCISED BARLEY ROOTs-Dimethyl sulfoxide (DMSO) in concentrations of up to 10% by volume stimulates the uptake of zinc by excised barely roots. In the same concentration it severely depresses uptake of sodium and of rubidium. It does not seem to affect the permeability of the membrane, since roots treated with desorption solutions which were 10% in DMSO did not lose more of the preferred ion than did roots desorbed in solutions not containing DMSO. Oxygen utilization (measured in the Warburg respirometer) was reduced when DMSO was present. It is suggested that DMSO is a poisoning agent which interferes with cation transport by attacking some aspect of metabolism and not by influencing the permeability of the membrane. TREEs-Radioisotopes are being used to measure rate and pattern of water movement in Pinus contorta and Abies magnifica. Purpose of the study is to develop a method for estimating the volume of water transported through tree stems under given conditions. Experiments have been conducted in the snow zone of the Sierra Nevada in different seasons. Injections into 60-year-old trees were made by immersing ellQ-S of small lateral roots, in situ, into vials of phosphorus-32 solution. Rate of upward movement was monitored with a portable scintillation detector, and pattern of movement was determined from radioautographs. Midwinter rates averaged 0.3-1.3 ern/hr. Some movement occurred even during periods of harsh weather. During spring and summer upward movement of the transpiration stream was as fast as 2 m/hr, No consistent differences between species were found. The channel of ascent in both species was narrow, and the paths of radioactivity tended to spiral dextrally. In the lower part of the boles the isotope was concentrated in the outer 2-3 em of sapwood, but radioactivity was found as deep as 6-8 cm during periods of rapid ascent. Techniques of injection and measurement are being improved in current studies in an effort to inject and measure radioisotopes in the tree sys.tem without affecting the physiology of the stem. Radioautography of~llcrotome sections is being used in an attempt to determine actual fiber-cavity space utilized in water transport under various environmental conditions.

Brown, H. D., A. B. Patel, and S. K. Chattopadhyay. Cancer Research Center, Columbia, Mo.-ETHYLENE-MALIC ACID COPOLYMER, AMINOPOLY-STYRENE AND POLYVINYLAMINE MATRICES FOR POTATO APYRASE-Linkage of enzymes to support matrices is a procedure which has both practical application an~potential utility in the elucidation of reaction mechanisms, That apyrase when affixed to a carboxymethyl celluloseazide matrix exhibits properties different from those seen when the same enzyme is in solution has been reported earlier. In order to further test the thesis that protein conformational changes imposed upon the enzyme by the matrix affect characteristics of the enzy~e activity, other supports have been used. Ethylene-malic acid copolymer, aminopolystyrene, and polyvinylamine have been covalently bonded to potato apyrase (from Sigma Chern. Co.). Properties of the solid-supported enzyme differed from the soluble activity and the seve.ral enzyme-matrix complexes exhibited properties which were different from each other. The level for optimal activation by calcium is 10-2 M for the polyvinylamineenzyme complex, 10-1 M for CMC azide-enayme complex; other preparations were identical with the soluble enzYIJ?-e in this character. K m values are: 0.09 mM for apyrase in solution; 0.63 mM for CMC azide-apyrase; 2.26 mM for polyvinylamine-apyrase; 2.35 mM.for E-MA copolymerapyrase; and 1.18 mM for ammopolystyrene-apyrase. OXYGEN-A few 1O-25-cm-long segments of excised apple branches with bark from 1 to 4 mm thick enclosed in an unventilated but slightly permeable polyethylene bag will naturally generate and maintain an atmosphere saturated with moisture and containing approximately 2% oxygen, 25% carbon-dioxide and 25 to 50 PPJ.ll of ethylene after a few days at room temperature. Within a week numerous white puffy masses of large, thin-walled (ells will protrude from the lenticles on the surface of the branches. Such proliferation continues for several weeks or longer if contamination can be avoided, and it may eventually involve vigorous meristematic activity that results in soft spongy succulent sheets of new cells between the several bands of periderm, while the outer thin brown layer is separated and splits off. The sheets of new cells remain white and turgid so long as the atmosphere remains humid, but they collapse and turn brown and powdery soon after exposure to dry air. However, no callus will be formed from the vascular cambium exposed at the cut edges of the segments unless the bag is ventilated through a few punctures, 1-3 mm III diam, Such ventilation can be adjusted to cause an increase of ?xygen in the enclosed atmosphere to about 10 to 15%, With the carbon dioxide falling to around 10%, and with ethylene remaining at a level of approximately 20 ppm without reducing the humidity too much. If an appropriate oxygen level and high humidity are provided at the outset and maintained throughout a period of several weeks, little or no proliferation from the bark tissues occurs, but abundant callus will be formed from the exposed vascular cambium, and a few latent buds will push out to produce short leafy shoots. The unexposed cambium between the phloem and the xylem becomes slippery and active enough to allow easy separation of .bark and wood~t all levels of oxygen that keep the tissue alive, even m the absence of active shoot growth from the latent buds. Ethylene naturally produced by the branch segments seems to be responsible for the initiation of meristematic activity, which can be greatly increased by enclosing a small apple in the bag, or by the introduction of a minute quantity of pure ethylene.

Parmar, A. S., and H. D. Hammond. Howard University, Washington, D.C.-THE EFFECT OF BORON AND GIBBERELLIC ACID ON THE SENESCENCE OF LEAF DISCS FROM LYCOPERSICON ESCULENTUM Mill., 'RUT-GERS'-The addition of 4.33 X 10-6 M gibberellin A a (GA), 1.0 X 10-6 boron, and GA plus boron to leaf discs of 'Rutgers' tomato retarded the senescence by delaying the degradation of chlorophyll, RNA, DNA, and protein.

Besides these effects they also checked the decreases in fresh weight and diameters of the leaf discs. The losses of chlorophyll, RNA, DNA, protein, fresh weight, and diameter of the leaf discs were 10, 30, 8, 20, 28, and 0% with GA alone; 15, 35, 8, 25, 31, and 0% with boron alone; 8, 25, 7, 14, 25, and 0% with GA plus boron; and 50, 50, 9, 40, and 3% in the controls. The manner in which GA treatment arrested senescence in tomato leaf discs may be similar to that shown by other growth regulators such as kinetin and auxin. It is suggested that retardation of senescence by GA in this case may be associated with the maintenance of DNA as a functional template for DNA-dependent synthesis of RNA. The effect of boron in retarding senescence may be related to its effect on sugar and starch balance, translocation of sugar, water balance, or perhaps nucleotide and protein metabolism in plants. Boron may play an important role in the synthesis of deoxyribonucleic acids. -The factorially designed experiment was designed to determine the effects of any interaction between boron (5.0 X 10-6 and 5.0 X 10-8 M), gibberellic acid (3.5 X 10-3 and 3.5 X 10-4 M) and kinetin (1.0 X 10-5 and 1.0 X 10-6 M) on the senescence of partially expanded leaf discs of Solanum aculeatissimum Jacq. Osborne (1962) demonstrated retardation of both protein loss and chlorophyll degradation in kinetin-treated leaf discs of Xanthium. Beevers (1966) demonstrated that nasturtium-leaf discs floated in gibberellic-acid solutions showed less than a 10% loss of chlorophyll and delayed decrease of RNA content. Gross morphological studies and analyses for chlorophyll, protein, RNA, and DNA demonstrated that discs treated with gibberellic acid, boron and kinetin in both high and low concentrations exhibited an initial increase of size, protein, chlorophyll concentration, RNA and DNA. This period of increase in activity was about 72 hr. It appeared that gibberellin and boron both affected the senescence phenomena. After 7 days the gibberellin and boron (in combination)-treated discs, on the average, demonstrated greater retardation of the manifestations of senescence. Kinetin, when acting in combination with gibberellin and/or boron, seemed to inhibit the aforementioned phenomena. It appeared that boron (5.0 X 10-8 M) when combined with kinetin retarded to a lesser extent the senescence phenomna than other combinations. Session 1. Thursday Afternoon. GRAEME P.

BERLYN, presiding. Physiological Section-continued other plant materials was prepared according to the procedure of J. Bonner for the isolation of chromatin, followed by purification according to J. Marmur. When heated, such preparations exhibit an increase in optical density at 260 nm that is assumed to be indicative of the progressive separation of homologous strands of DNA. Goldberg and Atchley have reported that the melting profile of placental DNA and other DNA was specifically modified by pertinent mammalian hormones. On the basis of a similar rationale, we have determined that the auxins, indoleacetic acid, napthaleneacetic acid, and 2,4-dichlorophenoxyacetic acid, as well as gibberellic acid, increase the melting rate of DNA extracted from whole etiolated 4-day corn seedlings. These auxins apparently expedite the thermal disruption of the double helix. Kinetin, tryptophan, and 2,3,5,-triiodobenzoic acid have no measureable effect on the same preparations. This effect may be valuable as an auxin assay that is independent of all enzymatic constituents of a plant cell.

Flynn, J. J. University of Massachusetts, Amherst-FINE-STRUCTURAL ASPECTS OF THE POLLEN TUBE CELL WALL-Pollen tubes of Impatiens holstii were grown in vitro and their cell walls were studied in thinsection and in negatively stained specimens after various procedures to selectively extract wall components. The cell wall consisted of an amorphous phase and a fibrous, cellulosic phase in addition to numerous vesicles and granules. Mter extraction of non-cellulosic materials with 17.5% sodium hydroxide, the pollen tubes remained morphologically intact and consisted mainly of fibrils 2-6 nm wide averaging 70 nm in length. The fibrils were randomly dispersed. Many of the fibrils had dislocations along their axes and certain fibrils appeared to be joined. 16-20 nm granules were noticed in some preparations. The granules stained intensely with phosphotungstic acid, and they were no longer apparent after chelation of divalent cations by ammonium oxalate. In section the pollen tube wall had either a lamellate or a foamy texture. The foamy texture was more common in young wall but could still be found in more mature regions. The number of lamellae in the pollen tube wall ranged from 10 to 20 and the thinnest lamellae were about 5 nm thick.

Kozlowski, T. T., and S. Sasaki. University of Wisconsin, Madison-IMPoRTANCE OF COTYLEDONS TO EARLY DEVELOPMENT OF PINUS RESINOSA SEEDLINGS-In recently germinated Pinus resinosa Ait. seedlings photosynthesis of cotyledons, as measured with an infrared gas analyzer, was variously reduced by shading, herbicides (atrazine, simazine, propazine, and monuron), or combinations of shading and herbicides. When CO2 uptake by cotyledons was completely blocked shortly after cotyledons emerged, the primary needles did not expand and dry-weight increment of seedlings was inhibited. When cotyledon photosynthesis was partially redued by herbicides, low light, or both of these, there followed a proportional decrease in expansion of primary needles and reduction in dry weight increment of seedlings. Cotyledon expansion appeared to depend largely on carbohydrate reserves, whereas expansion of primary needles utilized primarily current photosynthate.

Ball, Ernest. North Carolina State University, Raleigh--8oME EFFECTS OF MIXING CALLUS CULTURES UPON THE SOLUBLE PROTEINS ISOLATED BY· GEL ELEC-TROPHORESIs-Preliminary investigations have shown that compatible mixtures of calli grow in patte!ns .<\~f ferent from those in pure cultures. They may maintain a growing non-senescent state several times as long as the pure cultures in some cases. The cells of the two com-ponents affect each other and cause reciprocal morphological changes. Judging that such effects might be correlated with changes in soluble proteins, pure cultures and mixtures were extracted and the extracts were separated electrophoretically in a column of aerylamide gel. Preliminary results indicate that changes m protein components occur when two compatible calli are grown together as compared with those extracted from the pure components. In mixed calli, certain proteins which had occurred in pure cultures were missing, and conversely new proteins appeared which had not been in the pure cultures. This effect has also been clearly demonstrated with the isozymes of certain dehydrogenases and esterases. In total darkness the leaf showed three movement phases. During the first phase the leaf assumed the down position and exhibited small irregular movements. This phase averaged 18 hr in length, but the range varied from 5 hr to as long as 30 hr. In the second phase the leaves moved in short distinct cycles with an average of 6.6 hr per cycle over an amplitude of 90 degrees. This phase averaged 72 hr in length with a range of 36-103 hr. The third phase showed subtle rhythmic cycles averaging 24 hr per cycle. These cycles were the types normally seen in leaf movement studies but were relatively low in amplitude. Under continuous light the leaf movements persisted uninterrupted over the entire 7-day test period. The major rhythmic cycles averaged 28 hr with the angle ranging up to 90 degrees. Intermediate cycles within the major cycles averaging approximately 3 hr were observed.

Lippincott, Barbara B., and J. A. Lippincott.

Northwestern University, Evanston, Ill.-A HYPONASTIC AUXIN BIOASSAY-Apphcation of auxin to the primary leaves of 7-day-old pmto bean plants causes the lateral margins of the leaf blade to curl up and inward toward the mid-rib in a typical hyponastic response. Significant curling is observed within 2 hr after auxin application, and maximal curling with the lateral margins meeting (induced at response-saturating auxin concentrations) occurs about 6 hr after application. This change is readily measured and the response expressed quantitatively in terms of the margin to margin width of the curled leaf relative to the fully extended width of the leaf at its broadest point prior to auxin application. Slight curling can be obtained with auxin concentrations of 10-6 M, and the amount of curling is increased in proportion to the log of the auxin concentration to about 10-3 M. The leaves are most sensitive to auxin at about 7 da:ys after planting (leaf width 28 mm), and by day 9 (leaf Width 43 mm) the primary leaves no longer show a hyponastic response to auxin. Employing buffered solutions (0.1 M phosphate at pH 7), the response appears to be specific for auxins and compounds readily converted into auxins. The relative sensitivity of the bioassay is 2,4-dichlorophenoxyacetic acid > indole acetic acid > naphthalene acetic acid > indolebutyric acid» indolepropionic acid. The system provides a simple and sensitive means of measuring auxin concentration on intact green plants in a very short time. As such it appears ideally suited for many teaching purposes and for laboratories that have only an occasional requirement for an auxin bioassay, 2:30 Lippincott, J. A., and Barbara B. Lippincott.

The anti-auxin p-chlorophenoxyisobutyric acid has little effect when applied to primary pinto bean leaves in the absence of auxin. It effectively reduces the auxin-induced hyponasty of the primary leaves, however, when applied with auxin. Similar results were obtained with transeinnamie acid. Ferulic acid delayed the auxin response but was not otherwise inhibitory, while p-coumaric acid showed no observable effect in the presence or absence of auxin. Triiodobenzoic acid (TIBA), which alters normal auxin transport, produced hyponasty followed by epinasty of the primary pinto bean leaf when added to the dorsal surface of the leaf. Addition of TIBA to the ventral surface of the leaf induced only epinasty. In combination with auxin, TIBA can promote the auxin-induced hyponastic response or inhibit this response, depending on whether they are added singly or in combination to either the upper or lower surface. The data indicate that auxininduced hyponasty results from the movement of auxin from the upper to the lower leaf surface where it increases the growth of the cells of the lower surface. One part of auxin transport in the pinto bean leaf at this stage of development appears to be vertically polarized with auxin moving preferentially from the dorsal to the ventral side of the leaf.

Thompson, N. P. University of Florida, Gainesville-REGENERATION OF XYLEM AND AUXIN TRANSPORT IN PEANUT LEAVEs-The polarity of IAA-C14 and 2,4-D-C14 transport in isolated peanut leaf blades is predominantly basipetal. with 2,4-D-C14 being the more polar. Methods included apical and basal applications of IAA-Cu and 2,4-D-Cu, freeze-drying of leaf tissue 7 days later and radioautography of the leaves. Some groups of dried leaves were then rehydrated, boiled in ethanol for pigment removal, cleared in lactic acid, stained in basic fuchsin in ammonium hydroxide, and permanently mounted on glass microscope slides for anatomical study. Other groups of dried leaves were extracted with ethanol for auxin recovery. Auxin applied on the cut leaf blade tip caused regeneration of xylem cells around a horizontal wound which severed the midrib. Counts were made of xylem cells, bearing typically scalariform-reticulate wall thickenings, regenerating around the wound. Regeneration of xylem cells occurred in intact (wounded) leaflets and in those isolated leaflets to which auxin had been apically applied.

Blake, Clara. Brooklyn College, Brooklyn, N.Y.-NIACIN-TRIGONELLINE CONVERSION IN INBRED AND HYBRID CORN-Trigonelline, a methylated derivative of niacin, cannot be metabolized by man. The conversion of niacin to trigonelline, therefore, represents a loss of the vitamin for man's nutritional needs. A total of 16 lines of corn were used in embryo culture. They included four groups, each composed of the two inbred lines and their reciprocal crosses. Niacin was added to the culture medium of half of the cultures of each line. Seedlings were harvested in two fractions, shoot and root with cotyledon. They were extracted and the extracts were chromatographed. Microbiological assays of the eluates of the chromatograms were used to determine the niacin and trigonelline values. Preliminary results indicate that in all lines trigonelline increased in both shoots and roots when niacin was added to the culture medium. In general with few exceptions, the shoots contain more trigonelline than the roots and the roots contain more niacin than the shoots. The relationship of the niacin-trigonelline conversions within each group and among the groups will be compared.

Kalil, Millicent, and A. C. Hildebrandt. University of Wisconsin, Madison-8TILL AND CINEPHOTO-

Best') grown on nutrient media contained many starch granules. Starch content within the cells as seen in the microculture through the phase-contrast microscope was rated on a scale of 0-4. Young, active cells contained numerous large starch granules (Type 4) which typically surrounded the nucleus. Some older cells contained no starch granules (Type 0). Starch granules were identified with polarized light and 12KI and photographed with still and cinephotomicrography. The present study investigated relative amounts of starch in tomato cells in the microculture chamber; cells were both in direct contact with and separated by mineral oil from the crown gall tumor-inducing bacteria Agrobacterium tumefaciens (E. F. Smith and Townsend) Conn. Tomato cells in direct. contact with bacteria became less active after a short period and died within 24-36 hr. Tomato cells separated from bacteria by mineral oil divided to form colonies and contained less starch after 7 and 10 days than did normal aging cells. The role of the tumor-inducing bacteria in this increased starch degradation and their relationship to the tumorization process are under investigation.

Schenk, R. U., and A. C. Hildebrandt. University of Wisconsin, Madison-8oMATIC HYBRIDIZATION: A NEW APPROACH TO GENETIC CHANGE-8omatic hybridization offers an approach which circumvents many of the most serious problems encountered in current methods for genetic modification of plants. In this study the procedures necessary for somatic hybridization, including the requirements for cellular fusion, proliferative growth of cells, and differentiation into plants, were evaluated with tissue-culture methods. Methods for the initiation and proliferation of monocotyledonous cell cultures (callus) were also intensively studied. Germinating seeds were excellent sources for callus initiation in most dicotyledonous as well as monocotyledonous species tested, with the most consistent response being obtained in the presence of the growth substance, 2,4-dichlorophenoxyacetic acid. Kinetin was not essential for the induction or proliferation of callus of the monocotyledonous species studied. Proliferative growth was most consistent in the presence 0' the growth hormone, p-chlorophenoxyacetic acid. Sucrose was equal to or more effective than glucose as a carbon source. Citrate and succinate buffers were utilized in defined media to provide pH control in the pH 4.0-6.0 region, thus permitting control of the degree of ionization of the acidic auxins and basic cytokinins which influence cellular differentiation. Laboratory-extracted and commercially available cellulases were tested for their effectiveness in the dissolution of the rigid plant cell wall. Two commercially available cellulases yielded naked but dead protoplasts. These enzymes have been purified and concentrated, and further testing is continuing.

Kant, Uma, and A. C. Hildebrandt. University of Wisconsin, Madison-CYTOMORPHOLOGICAL STUDIES OF EDIBLE PLANT TISSUES IN TISSUE CULTURE-Cytomorphological features were studied of callus tissues established from carrot root, endive embryo, leaf petiole and stem of lettuce, leaf petiole of parsley and spinach, and navy bean and red kidney bean stem grown on solid C or D medium. The callus tissue of carrot, endive, lettuce leaf petiole and stem, parsley, and red kidney bean were irregularly lobed while the callus tissues of navy bean and spinach were hemispherically lobed and somewhat flattened, respectively. The cultures of carrot and endive were firm and massive while the calli of other species were friable. Callus cells of these seven specieshexamined with the phase microscope, varied in size and s ape. The callus cells of carrot, parsley, lettuce stem and spinach were spherical, oval and elongated. Elongated cells ranged from 204-389 p, in length by 45-53 p, in width, spherical cells 80-129 p, in diam and oval cells 118-172p, in length by in width. Variations were noted in the morphol-' ogy and number of cell inclusions including the nucleoli, plastids, mitochondria and starch granules. In chlorophyllous cells the chloroplasts were generally scattered III the cytoplasm and often surrounded and obscured the nucleus. Varying numbers of starch granules were seen around the nucleus and in the cytoplasm.

Wallace, J. W. Western Carolina University, Cullowhee-e-S'rtmras CONCERNING THE BIOGENESIS OF C-GLYCOSYLFLAVONEs-Previous research has indicated that C-glycosylation is not a terminal reaction during the synthesis of C-glycosylflavones in the Lemnaceae. C-glycosylation of flavone aglycones did not occur during the biosynthesis of either 6-C-or 8-C-glycosylflavones, nor were 6-C-mono or 8-C-mono-C-glycosylflavones found to be C-glycosylated to 6,8-di-C-glycosylflavones. These data did not indicate when C-glycosylation actually occurred. The hypothesis was presented that the Cglycosylation reaction could have occurred at the chalcone or prechalcone stage of C-glycosylflavone synthesis. Subsequently Spirodela polyrhiza plants have been grown axenically in media containing labeled 2',4,4',6'-tetrahydroxychalcone 2'-glucoside in addition to mineral nutrients and sucrose. Radioautographic studies of the chromatographed methanolic extracts from these plants showed that the chromatographic area representing luteolin 7-O-glucoside contained radioactivity, whereas the areas corresponding to orientin did not. These data indicate that the chalcone aglycone was not a precursor to the C-glycosylflavone in S. polurhiea. Since chalcones have been shown to be precursors to all flavonoids studied, it is hypothesized that if C-glycosylchalcones are precursors to C-glycosylflavones then the C-glycosylation reaction probably occurs prior to the chalcone stage in biosynthesis.

Kadkade, P. G., and M. L. Jain. St. Louis University, St. Louis-PHYSIOLOGICAL EFFECTS OF CAR-CINOGENIC AROMATIC AMINES ON DWARF BEAN PLANTS-The finding that certain aromatic amines possess exceedingly potent carcinogenic activity prompted the investigation of what effect, if any, these compounds may have on the physiology of plant cells and how plant growth and development may be affected. Carcinogenic aromatic compounds used in this study were: acetamidofluorene (AAFL), aminofluorene (AMFL), and p-dimethylaminoazobenzene (DAB). These chemicals were applied to the apical meristem of the dwarf bean shoot. This was done after the complete emergence of primary leaves and before the development of first trifoliate leaves. After 96 hr of application the total reducing and hydrolyzable sugars in the primary leaves significantly increased. This effect was more pronounced in the case of AAFL and AMFL. The increase in sugar content was correlated with the increase in hydrolytic enzymes involved in carbohydrate metabolism, viz., invertase and amylase. These compounds also increased total soluble proteins and indole-acetic acid content of primary leaves. Additional effects such as various morphogenic responses will be discussed. shastense appear to exist presently at the type locality, whereas the other two species are abundant there and often occur in mixed stands. In Wa~hington, at two locations where P. scribnerianum occurs syrnpatricallv with members of the Lanuginosa group, three morphologically intermediate plants were found and are thought to be first-generation hybrids. Nine hybrid plants have been produced in the greenhouse between P. scribnerianum and two members of the group Lanuginosa. Parental plants consistently have a chromosome number o" 2n = 9rr, meiosis is regular, 90% of the pollen grains are evenlv stainable, and seed set is high. The putative hybrids, including P. shastense, and the artificial hybrids have It similar combination of characters, only about I}% of their pollen grains are evenly stainable (except for l.'i% in one artificial hybrid) and none has produced seed in the e;reenhouse. Meiosis in the hybrids is characterized by a hieh frequency of paired chromosomes ann a low percentage (15-30%) of univalents, lagging chromosomes, and micronuclei. It. is suggested that P. shastense is a rarely formed sterile hybrid between P. scribnerianum and P. pacijicum. In the course of preparation of Botanico-Periodicum-Huntianum, a compend'um of data on the world's periodical literature of the last 300 years, a set of internationally acceptable, non-ambiguous. standardized abbreviations has been developed for citation of titles. In addit'on to meeting the requirements of accentahility within the linguistic framework of more than 45 included languages, consideration was also given to prior usage in botanical reference works. The result is a unified set of abbreviations and standards for abbreviations which have been evaluated ona broader basis than has been possible prior to the use of computer analyses.

Crovello, T. J. University of Notre Dame Notre Dame, Indiana-EFFECT OFCHANGE OFCHARACTERĨ N .NUMERICAL TAXONOMY-Infor~ation on 214 morphological characters~or 30 taxospecies of the genus Salix, Willows, was obtained, Ten analyses were made using different sub-sets of these characters. The purpose of these analyses was to determine whether different analyses yield different results. Each analysis used the same coefficient of distance in Euclidean space to obtain similarities among the taxospecies. The unweighted-pair group method (averages) was used for cluster analysis. Results reveal different clusters of taxospecies with each analysis, although certain groups of them remained invariant in most of the analyses. In the absence of other information those analyses using all available data are judged tẽ stimate best the phenetic relationships among taxospecies in the context of all possible characters.

Macior, L. W. University of Akron, Akron Ohio-INSECT POLLINATION AND AI,PINE ANGIOSPERS PECIATION-Data from current ecological and phenological investigations of sexual reproduction and bumblebee (Bombus Latr.) pollination adaptation in angiosperms of the Colorado Front Range montane and alpine zones suggest strong seasonal interdependence and evolutionary coadaptation between flowers and insect foragers. Plant species having flowers mechanically adapted to bumblebee form and behavior show vertical distribution patterns correlated with those of Bombue species. Such flowers are infertile in the absence of bumblebees and at higher altitudes may in some cases be infertile even in their presence. Phenologically restricted plants of the alpine tundra exhibit marked forager specificity corresponding to caste development in the annual Bombus colonies. In these circumstances plant species having similar flowerform and/or pollination mechanisms appear to share the same pollinators. At lower elevations the pollinator species spectrum is broader. but still phenologically determined by forager form and abundance. Congeneric plant species exhibiting mutually disjunct vertical distributions are pollinated to a substantial degree by different Bombus species, but pollinator species with wide vertical distributions may effect some degree of ltene flow between them. Hybridization by diurnal vertical foraging migration of pollinators is presently restricted to circumstantial evidence. Further studips on the high alpine tundra are planned to determine the nature and degree of obligate interdependence of angiosperms and their pollinators under high selection pressures of the environment. Systematic Section-eontinued throughout northern Florida. This study was initiated to ascertain the relationships of these taxa. Representative clones were placed in cultivation in the research garden of The Ohio State University and analyzed morphologically by means of pictorialized scatter diagrams. The results indicated that S. compositum val'. reniforme arose by hybridization of S. compositum val'. compositum and S. terebinthinaceum Jacq. followed by repeated backcrossing to the former parent. Both artificial hybrids and a putative natural hybrid support this assumption. The intermediate forms of the two varieties on the Piedmont may represent other backcross segregates. Silphium venosum is morphologically and geographically intermediate between S. compositum val'. compositum and S. ovatifolium and may have arisen by allopatrie introgression. Analyses of natural populations by means of Gay's hybrid number method and polygonographs also indicate the close relationship of these taxa. Individual populations are rather homogeneous; however, variation between populations is continuous. This results in character clines extending eastward and southward. This study suggests that these four taxa be considered subspecies of S. compositum.

Kern, Patricia. University of Washington, Seattle-BIOSYSTEMATIC STUDIES OF THE THLASPI MON-TANUM (CRUCIFERAE) COMPLEx-This study was undertaken to determine the relationships of the North American perennial species of Thlaspi to their Eurasian and South American counterparts. Because of their diverse morphology and habitat-preference, taxonomists have described extremes of the variation pattern as 14 species and 3 varieties in North America alone. Plants transplanted into the greenhouse as well as those grown to maturity from seed derived from the same populations were compared morphologically with the original field collections partially to determine whether the variation was genetically controlled or environmentally induced. Controlled intrapopulational and interpopulational crosses followed by tests of pollen stainability and cytological analysis of the F1 and F 2 generations were made. Evidence resulting from the experiments on hybridization and cultivation-transplantation, and from the study of the c:ytology, breeding system, and gross morphology, combined with field observations, suggests that the majority of our plants cannot be separated even infraspeeifically from the Eurasian T. montanum L., although several infraspecific units of that taxon are recognized for North America. Only one other perennial species is recognized for North America, the self-pollinating T. parvijlorum A. Nels., occurring in Idaho, western Wyommg, and Montana.

POLYPHENOLs-The foliage polyphenols of 16 Pinus species were compared by two-dimensional paper chromatography. The general patterns of chemical similarity were correlated with the geographic distributions of the species; sympatric species generally_ had greater chemical affinity than did allotropic species. This relationship did not always correspond to hybridization patterns and morphological similarities. The distinctive chromatographic patterns of the Southeast Asian species (P. insularis, P. luchuensis, P. merkusii) and their generally low affinities with species of Europe and the Asian mainland suggest that further investigation of the morphological relationships and the genetic compatibility of these species with other Sylvestres species is warranted. The chemical relationships of P. halepensis and P. heldreichii to other Sylvestres species were also unclear. The qualitative differences in polyphenols among species are consistent and of sufficient magnitude to enable the application of chromatographic analysis to studies of interspecific hybridization in Pinus.

Hills, H. G. University of Miami, Coral Gables, Fla.-ROLE OF ORCHID-FLOWER FRAGRANCE IN POLLINATOR SPECIFICITY-Species specific pollination in the sub-tribes Catasetinae and Stanhopeinae of the family Orchidaceae is directly related to the fragrance produced by the orchid flower. Pollinator specificity is the primary barrier to hybridization of species within these sub-tribes. Knowledge of the flower fragrance is therefore essential to understanding the taxonomy of these orchids. Gas chromatographic techniques have shown that where there is a specific pollinator of an orchid species there will also be a distinctive fragrance produced by the flower associated with the specific pollinator. Compounds identified from the flower fragrances are of several types. Field tests in Panama and other South and Central American countries indicate that 1,8-cineole and methyl salicylate are general attractants. Benzyl acetate, d-carvone, linalool, and methyl benzoate appear to be specific attractants. Other compounds such as a-pinene and~-pinene appear to be neutral or repellent. By mixing the co~ pounds identified in the proportions that they occur III the flower fragrance, the specific pollinator can be attracted. alliance, comprises four morphogeographic races which replace each other in shallow winter-wet soils around the borders of the Columbia Plateau in eastern Washington and Oregon. There is no morphological or geographical overlap among the races, but the distance between the closest two is only 10 miles. All races are diploid with 2n = 14 chromosomes. Chromatograms representative of the complex revealed 53 different spots. Each race has a characteristic pattern of flavonoid-like components which is distinct from those of the other varieties. It is concluded that Allium douglasii is an assemblage of closely related taxa which replace each other in a linear fashion, possibly in p,hylogenetic sequence, thereby forming a "Rassenkreis. '

Stuessy, T. F. The University of Texas, Austin-SYSTEMATICS OF THE WHITE-RAYED SPECIES OF THE GENUS MELAMPODIUM (COMPOSITAE: HELIANTHEAE)-All but two of the species of the genus M elampodium have flowering heads with yellow or orange-yellow rays. The two white-rayed species, M. leucamihum and M. cinereum, found in Texas and neighboring areas have been imperfectly understood in the literature and ,in herbarium records. In the present treatment two species are recognized and chromatographic pattern data are used to support this decision. Although M. leucanthum is morphologically very homogeneous, two distinct chromatographic patterns, which indicate east-west chemical races within the species, are found. The significance of these chemical patterns to the evolution of both species is discussed. The other species, M. cinereum, is morphologically heterogeneous but clearly can be divided into three varieties; one of these varieties, however, possesses two distinct morphological entities presumably representing two cytological levels. Evidence for the tetraploid level resulting from spontaneous autopolyploidy is discussed. Finally, the evolution of the two species is considered and .eomments regarding their relationship to the other members of the genus are also included.

Cooperrider, T. S. Kent State University, Kent, Ohio-CYTOTAXONOMY OF CHELONE (SCROPHULAR-IACEAE)-In the most recent revision of Chelone, that of F. W. Pennell in 1935, four species were recognized: one with seven subspecies, one with three subspecies, and two not divided into subspecies. Chromosome counts for the 12 taxa show three different numbers in a euploid series based on n = 14. For the most part distribution of the numbers is not in disharmony with the specific lines drawn by Pennell. One new taxon has been discovered. Preliminary results from a cross-breeding program indicate, generally, the presence of reproductive barriers between taxa having different chromosome numbers. Of these species, H. villosa represents a highly variable taxon consisting of quite diverse but intergrading geographical races and often much local variation. Common garden studies indicate that most existing variation within this complex has a genetic basis. The analysis of hybrids obtained between most of the recognized species of the complex and between the various races of H. villosa tends to support the postulation that the variable, tetraploid species, H. villosa, has had a polyphyletic origin.

Stuckey, R. L. The Ohio State University, Columbus-WESTERN LAKE ERIE'S CHANGING AQUATIC AND MARSH FLORA-Floras are continually in a state of flux and any contemporary floristic analysis should take into account those changes in species composition that have occurred through time and the possible factors affecting those changes. The aquatic and marsh flora at the western end of Lake Erie provides an opportunity for this type of study because of the habitat and land-use changes that have been occurring in the marshes, bays, rivers, and ponds since the advent of European man. Furthermore, several previous detailed floristic surveys dating from 1900 onward provide historical data for comparison with information obtained in recent field studies. These comparisons indicate that once common species, such as Typha latifolia, Sagittaria rigida, Phragmites communis, and Zizania aquatica are now rare. Their habitats have become occupied by previously infrequent or rare native species, such as Typha angustifolia, Sagittaria latifolia, Phalaris arundinacea, Calamagrostis canadensis, Hibiscus palusirie, and H. militaris. Submersed aquatics (e.g., Najas jlexilis, Megalodonta beckii, Vallisneria americana, Elodea canadensis, and several species of Potamogeton) which formerly were more abundant are now rare or absent. Naturalized species such as Potamogeton crispus, Butomus umbellatus, Rorippa sylvestris, and Lythrum salicaria are now common in certain portions in the area. More recent invaders presently known to be restricted to a few localities are Epilobium hirsutum, Lycopus asper, L. europoeus, Mentha gentilis, Najas marina, N. minor, Phalaris comariensis, Polygonum orientale, and Ranunculus bulbosus. Possible factors affecting changes in species composition, particularly with reference to the disappearance of the native submersed plants, have been suggested to be (1) carp feeding habits, (2) habitat changes about the margin of the lake, and (3) increased turbidity and silting primarily brought about by land use changes in the lake's western drainage basin. Other possible explanations for the observed floristic shifts bear further investigation.

Crovello, T. J. University of Notre Dame, Notre Dame, Indiana-NuMERICAL TAXONOMY: ITS VALUE TO BIOSYSTEMATICs-Taximetric techniques have been used primarily to describe the phenetic pattern of variation among taxa (OTU's). The results provide classes of taxa which may help the investigator in his formal taxonomic decisions. But the same set of data used for grouping taxa can also be used to carry out the inverse analysis, the grouping of characters. It is suggested that the results of such a character analysis have great heuristic value for biosystematics and can serve as an efficient context for generating hypotheses of evolutionary importance which can then be strengthened OJ: disproved by regular biosystematic methods. As an illustration, a recent study in the Limnanthaceae will be presented. Although Hitchcock used no tribal designations in the work referred to above, it can be assumed that he considered Triniochloa to be a member of the Agrostideae, since he placed it next to Muhlenbergia. In subsequent publications (in which tribes are indicated) this same arrangement is followed. Other authors have continued this alignment with the exception of Pilger (19.'>4), who assigned Triniochloa to the Stipeae. Recent studies of the type species, T. siipoides, utilizing cytological and anatomical techniques in addition to traditional methods, suggest that the affinities of Triniochloa are with the Meliceae. As in other members of this tribe the leaf sheaths are closed, the ligules are membranous, and the lodicules are truncate and lack vascular traces. The chromosome number of 2n = 32 suggests that this species is a tetraploid with a basic number of x = 8. The chromosomes are small as in other members of the Meliceae, but in the others the basic number is usually x = 9 or x = 10.

The leaf anatomy and epidermis exhibit festucoid characters, as does the embryo. Triniochloa appears to be related most closely to Schizachne, with which it shares many gross morphological as well as more fundamental characters. ' 10:00

Tryon, Alice F. Harvard University, Cambridge, Mass.-EvOLUTIONARY STUDIES IN A GROUP OF COSTA RICAN FERNs-The genus Eriosorus is predominantly Andean ranging from Bolivia to Mexico. In Costa Rica' there are four distinctive species more closely related to South American species than to each other, Meiotic chromosome numbers for each of the species and for the related param6 genus, Jamesonia, are uniformly 87. These evidently represent hexaploid levels derived [Vol. 55 Systematic Section-continued from a base of 29. Geographically they appear sympatric; however, each species has its own habitat or altitudinal range. Eriosorus congestus is small and erect; plants are widely distributed in open areas below 2300 m. Eriosorus f/laberrimus is scandent and grows on mossy tree trunks III forests. Hybrids between these occur in clearings where E. congestus has invaded cutover woodland. Eriosorus fiexuoeu» has a scrambling habit growing on thickets at higher elevations. Eriosorus Warscewicz# is small and erect, occurring near mountain summits. On Volcan Polis this grows with E. fiezuosu« and there the two form numerous hybrids. It also occurs on Cerro de la Muerte in the Talamanca range, growing in dense clumps with J amesonia Scammanae, and hybrids between these genera are abundant. Population samples of all of these hybrids have largely shriveled spores and at meiosis there are usually ca. 174 univalents although some pairs may be formed. The uniform ploidy level in all of the species supports morphological evidence for their independent relationships in South America. Hybridization between these high polyploids demonstrates the manner in which the very high chromosome numbers so frequently encountered in the ferns may originate.

Hunter, G. E. Tennessee Technological University, Cookeville-c-Sroxxrar, ARRANGEMENT, NODAL AND PETIOLAR ANATOMY OF MEXICAN AND CENTRAL AMERICAN SAURAUIA (DILLENIACEAE)-Anornocytic stomatal arrangement was found in leaves of 11 species of Mexican and Central American Sourauia. Guard cells in all were surrounded by at least three epidermal cells. The nodes of specimens of six species were unilacunar with a single broad canaliculate trace. Serial sections of petioles reveal that trace configurations reach a level of complexity at the middle beyond which only minor changes occur. Samplillg at the three-quarter level showed that petiolar-trace configurations were quite varied for 100 specimens of 22 species. Three basic trace configurations were recognized: (1) traces canaliculate, (2) traces solenoid, and (0) traces solenoid with intramedullary vascular tissues evident. The range of intraspecific and interspecific variation in the petiolar trace makes this feature of little use for distinguishing species of Saurauia and casts doubt upon its usefulness for showing familial relationships.

Long, R. W. University of South Florida, Tampa--8oME OBSERVATIONS ON THE FLORA OF SOUTHERN FLORIDA--8outhern Florida is an area long recognized as having a unique flora in the continental United States. Although a number of floristic and ecological investigations of this region have been conducted in the past, the area has not received a modern taxonomic account. An investigation is now nearing completion that will result in a manual for use in the description and identification of its plants and plant communities. During the course of this study some statistics have been prepared regarding the floristic composition, including information relative to the tropical and non-tropical elements in the flora, apparent relationships of the flora to that of other phytogeographical divisions, and the principal plant communities and associations. Special attention has also been given to the flora, particularly as it compares with accounts given by previous workers, and to critical groups of plants such as established exotics, endemic species, weed species, and species-complexes. The total flora of approximately 1,500 taxa of vascular plants is largely tropical in origin and the various'communities are remarkably uniform. The apparent limits of the flora . . in southern peninsular Florida are identified. Some of the effects of land development and changes of the local environment on the flora are discussed. Previous studies on microscopic leaf characters have indicated that the cuticular patterns of the lower leaf surface are species-specific in Vaccinium, and that with hybridization the specific patterns break down and result in patterns different from the parental types. Since Vaccinium vacillans and V. tenellum have distinctive leaf shapes, presumed hybrids between them can be recognized by leaf shapes of varying degrees of intermediacy. Variability in 10 variable populations of these two species was studied with respect to cuticular pattern and to leaf morphology. The leaf morphology was evaluated by a graph using leaf-shape characters as coordinates and by a polygonal graph using various leaf characters. Hybrid Index values based on these characters were also used to determine the degree of presumed hybridization of each plant. Trends in variability in leaf-shape characters differed from one population to another; trends established within one population were reversed or nonexistent in other populations. On'y a general correlation between leaf shape and cuticular pattern was established, in that plants of "hybrid" cuticular pattern had intermediate leaf shapes. Of the 150 plants of V. vacillans and V. tenellum studied with respect to leaf characteristics, nearly one-third were determined to have leaf characters of varying degrees of intermediacy. Further study and knowledge of the other species in the section Cyanococcus with which V. vacillans and V. tenellum are known to hybridize are necessary before the relationships are better understood and any nomenclatural changes are made in the genus Vaccinium.

Ornduff, R. University of California, Berkeley-NEoTROPICAL NYMPHOIDES: THE CASE FOR TAXONOMIC PROVINCIALISM-The species of Nymphoides (Menyanthaceae) are distinctive when living; however, herbarium specimens of many of the tropical species are virtually impossible to identify. As a result the taxonomy of the tropical species is confused. In the New World tropics there are at least four taxa of the genus. Num-»hoides ftaccida occurs in a small area in the Colombian llanos and is easily recognized because of its distinctive foliage. It apparently does not reproduce sexually awl this may account for its restricted distribution. The taxon generally called N. humboldtiana is inseparable from white-flowered forms of N. indica of the Old World and the two should be considered conspecific. The yellowflowered Bahaman N. aurea is identical in floral morphology to N. indica; such yellow-flowered populations are sometimes given separate specific status in the Old World. In Mexico and Guatemala there is another yellowflowered species which is either unnamed or is conspecific with a Cuban species whose identity is unknown and is unlikely to be forthcoming in the future. A correct nomen-clature for the neotropical species is impossible without revision of the paleo tropical species. In view of the unlikelihood that such a revision will be forthcoming, and because of the necessity of applying names to the neotropical species, it is suggested that the New World Nymphoides should continue to be called by their traditional, although possibly incorrect, names. The characteristic morphological appearance most people associate with the Umbelliferae is found principally in one of the three subfamilies, Apioideae. In the other two subfamilies, Hydrocotyloideae and Saniculoideae, the presence of "un-umbelliferous" morphological appearance is more characteristic. In an attempt to increase our knowledge of the relationship of these three subfamilies seed proteins from selected Umbelliferae were compared using serological and disc electrophoretic methods. Data indicate that the subfamilies can be separated on the basis of protein chemistry and that within the Apioideae a high degree of protein heterogeneity is present.

Keating, R. C. Southern Illinois University, Edwardsville--MoRPHOLOGY OF THE FL'OWER AND POLLEN IN THE COCHLOSPERMACEAE AND BIXACEAE-It has been said that it is largely a matter of opinion whether the Cochlospermaceae and Bixaceae should be combined or should remain as separate families. This attempt to resolve the question was based on a study of flowers from Cochlospermum, A moreuxia and Bixa from throughout their geographic ranges. Their flowers are usually considered as unspecialized with five free petals alternating with five free sepals, numerous stamens on a broad receptacle, and a two-or three-to five-carpellate pistil. At the base of the receptacle a siphonostele vascularizes the perianth with two flat spirals of five traces each to the calyx and corolla. The stamens are vascularized by five or more trunk bundles which divide into traces in a centrifugal pattern. Controversy over the nature of the septa in the gynoecium in the CocWospermaceae is solved by recognition of their anatomical nature as fused carpellary walls. Analysis of characters reveals numerous differences between Biza and the genera Cochlospermum and Amoreuxia. These include vestiture of the flower, nature of the gynoecium, form of the anthers, and several differences in pollen morphology. These data plus previously reported vegetative morphology support the concept that these families are related but should not be combined into one family. While Cochlospermum, Amoreuxia and Bixa show some relationship with the Flacourtiaceae, there is a stronger resemblance to certain families of the Malvales.

Levy, M., and D. A. Levin. University of Illinois, Chicago Circle--SEcoNDARY INTERGRADATION IN PHWX PILOSA-Phlox pilosa subsp. pilosa and P. pilose subsp. fulgida undergo secondary intergradation along It front extending from the southern tip of Lake Michigan across central Illinois, central Missouri, and southward into southeastern Kansas. Morphological character gradients in the intergrade zone are steeply sloping and highly irregular, and neighboring populations often are very dissimilar. Levels of morphological intermediacy. and variability are correlated with pollen fertility. Reduced fertility, which does not have a chromosomal basis, is associated with the production of polyploid pollen grains and with reduced anther size. Gene flow across the zone is further retarded by moderate crossability barriers. It may be inferred that the genomes of the two subspecies are moderately incompatible.

Morse, L. E. Michigan State University, East Lansing-CoNsTRUCTION OF IDENTIFICATION KEYS BY COMPUTER-Key construction by computer is superficially similar to numerical taxonomy, but it -differs in that taxa rather than specimens are the fundamental working units, and proper identification rather than classification is the goal. Indeed, the distinguishing features of the taxa must be determined before a key can be constructed. Once this is done, a multitude of keys can usually be produced, of which only a few are acceptably convenient and reliable. The approach is founded on the statistical conclusion that in general the best key to a given group of taxa is the one which approaches equalization of the number of taxa in the two subgroups formed by each dichotomy. However,this method must be modified since other factors are also involved. Weighting of characters is definitely advantageous, as is consideration of how frequently a particular taxon will be encountered by users of the key. The most common taxa should be identified in the fewest steps. Variable taxa offer the choice of lengthening the key by placing them in both subgroups of a dichotomy, or of reducing the overall quality of the key by using a character which is in general less useful. By varying the way these parameters are combined into character-selection criteria, several keys can be obtained from the same data, and the best one for a particular use can then be selected. In the program the data are submitted in three files. First the taxa are listed by name, and a reference number is assigned to each. Next a series of numbered statements is prepared, describing the characters potentially useful as leads in a key. Third, a data table is prepared giving the status of each taxon for each character. For this table a four-symbol code is used, indicating whether a particular characteristic is expressed by all specimens of a taxon, expressed by some, expressed by none, or is not determinable for the taxon. Using whatever character-selection criterion the taxonomist specifies, the computer constructs the best key possible from the data given. The output of this program is a set of numeric records from which a conventional key is generated and printed by a second program, which can also be used independently for revising and editing previously prepared keys. Output is in either the indented or the bracketed style, and as many copies as desired can be produced.

Gould, F. W. Texas A&M University, College Station-CHROMOSOME NUMBERS OF TEXAS GRASSES-The flora of Texas includes 572 species of grasses, 469 native and 103 introduced or adventive. One or more chromosome counts have been recorded for 409 (72%) of these taxa. Of the species for which chromosome numbers Systematic Section-continued have been reported, 121 (30%) are diploid, 123 (30%) are tetraploid, 48 (12%) are hexaploid or higher, and 117 (28%) have two or more ploidy levels. In a report now in press, 304 chromosome counts are presented for 140 species of Texas grasses. Twenty-two of the counts are the first for the species or different from previous records. The records of 2n = 60 for Neeragrostis reptans, 2n = 40 for Triplasis purpurea, and 2n = 40 for Gymnopogon ambiguus are the first for any species in these genera. The count of 2n = 14 for Panicum reptans confirms an earlier record of this most unusual chromosome number for a panicoid grass.

Gunn, C. R. New Crops Research Branch, U.S.D.A., Beltsville, Md.-COMMON STRANDED SEEDS AND FRUITS FROM THE SOUTHEASTERN SHORE OF FLORIDA-Beaches of the northern latitudes contiguous with either major or minor arms of the Gulf Stream receive tropical debris. The debris originates in the Caribbean Islands and the boreal South American area as ejecta of rivers and flotsam of storms. Among this tropical debris are seeds and fruits, whose characteristics may have been altered by the eroding and scouring action of sand and water. In addition to correctly identifying the stranded seeds and fruits, observations are made concerning their ability to float and to remain viable during the time they are in salt water.

Mitchell, W. W. University of Alaska Agricultural Experiment Station, Palmer-POLYPLOI15Y, ANEU-PLOIDY, AND CHOROLOGY OF SOME ALASKAN GRASSES-Alaska contains large tracts of land that were unglaciated while other areas were repeatedly ice-ridden during the glacial ages. Populations and ranges of plants have fluctuated accordingly. High polyploidy and aneuploidy characterize some groups of grasses that have survived in refugia and recolonized deglaciated terrain. Certain trends appear evident in the degree of polyploidy and aneuploid development as related to chorology in these groups, Other successful groups of grasses are very stable in. ehromosome number with a relatively low degree of polyploidy and little or no aneuploidy. Diploid species are few. The possible bearing of this study on previous theories concerning the adaptive significance of polyploidy in the northern regions is discussed.

Flinck, Allen, and D. M. Smith. University of California, Santa Barbara-CoNTRASTING PATTERNS OF CHEMICAL VARIATION IN MICROSTERIS GRACILIS-A diminutive annual relative of Phlox, Mierosteris gracilis (s, i.), forms small inconspicuous colonies in much of western North America. Local populations often show distinctive morphological features; thus Greene described numerous species within the group. Individuals comprising a colony are usually uniform and autogamous. A qual'tative chemical analysis of the flavonoid glycosides of Microsteris demonstrates that individuals from a particular colony are remarkably uniform in flavonoids but that colonies differ. An important exception to this general pattern is found in the Wallowa Mountains of Oregon, where conspicuous morphological and chemical variation was found. These plants, furthermore, were being visited by pollinators and autogamy could not be demonstrated. Most populations seem to be pure inbred genetic lines, but allogamy evidently exists in certain regions where recombinant types are found.

Scora, R. W. University of California, Riverside-DIVERGENCE IN MONARDA (LABIATAE)-A phylogenetic evaluation of the genus Monarda, based upon biological divergence including anatomical, chemical, cytological and morphological characters, is presented. The evaluation is patterned after the Wagner Divergence Index. Of 118 classical taxonomic characters found in the genus Monarda, only 31 were considered to have recognizable evolutionary tendencies, and of 26 chemical oil constituents only 9 were judged to have evolutionary significance. The genus is introduced and a botanical phylogeny is presented. The monoterpenes found in the genus are discussed and correlated. The evolutionary values of these terpenes are determined through a biosynthesis study with radioactive isotopes. This chemical information resulted in a vastly refined and expanded phylogeny of the genus Monarda. series such as orientin, iso-orientin, vitexin, iso-vitexin, etc., characterizes species of Tragopogon on two-dimensional paper caromatograms. The inheritance of these compounds has been studied in a series of 10 interspecific hybridization experiments in which the distribution of these and other flavonoids has been determined in parents, reciprocal F, generations, and in approximately 50 F 2 individuals. Certain compounds are inherited as single Mendelian factors, but others involve more complex genetic mechanisms. The genetic studies are particularly significant in analysis and interpretation of chromatographic patterns for evolutionary and systematic studies of Tragopogon.

Lee, D. W., and D. E. Fairbrothers. Rutgers-The State University, New Brunswick, N.J.-COMPARA-TIVE PROTEIN INVESTIGATIONS OF THE TYPHACEAE AND OTHER MONOCOTYLEDONs-8erological techniques were employed in comparisons of the seed proteins of Typha with other genera in the monocotyledons. Antisera against Typha species and Sparganium americanum were employed in the research. PreliIninary tests indicate some serological affinities between seed proteins of Typha and Sparganium. Slight reactivity was also noted between Typha antisera and antigenic extracts from Juncus and Scirpus. The results were evaluated in light of present systematic knowledge.

Levin, D. A. University of Illinois, Chicago Circle-THE EFFECT OF COROLLA COLOR AND OUTLINE ON INTERSPECIFIC POLLEN FLOW IN Par.ox-c-Interspecifie pollen flow in Phlox was measured from P. glaberrima toa series of P. drummondii cultivars which varied in corolla color and outline. The size of the pollen of these species differs conspicuously and therefore a stigma inspection readily reveals the number of alien grains. Pollen from P. glaberrima, whose corolla is red-pink, was transported most often to the pink, lavender and magenta phases of P. drummondii, and infrequently to the red and white phases. Pollen from P. glaberrima, whose corolla lobes are entire, was carried primarily to the entire-lobe form of P. drummondii as opposed to the laciniate-lobe form. These facts indicate that Phlox pollinators, primarily butterflies, can discriIninate strongly between certain groups of colors and not others, and between conspicuous differences in corolla outline. Thus differences in color and outline may play a major role in ethological isolation.

Smith, D. M. University of California, \Santa Barbara-CHEMICAL VARIATION IN PITYROGRAMMA TRI-ANGUL.uus-The California gold-back fern, Pityrogramma triangularis, produces an externally secreted substance which imparts the yellow or golden color to the back of the frond. This exudate is often a highlr pure chemical substance, ceroptene, whose structura details have previously been determined. Ceroptene-producing plants are easily recognized, since the fronds fluoresce bright yellow in ultraviolet light and give a bright red-orange reaction with ferric chloride, but not all plant'> of this species produce ceroptene. Those which do not produce an array of flavonoid aglycones. Superficially the two types of plants are alike, but the flavonoid-producing plants yield a green reaction with ferric chloride and fluoresce dull orange in ultraviolet light. The significance of these chemical differences will be discussed in terms of geographical distribution, genetics, biosynthesis, and relationship to polyploidy in the group.

Wall, J. R. Texas Technological College, Lubbock-STARCH-GEL ELECTROPHORETIC ANALYSIS of SEED PROTEINS OF TWO SPECIES OF PHASEOLUS AND THEIR HYBRID,s-8tarch-gel electrophoretic analysis of crude seed (cotyledonary) extracts of Phaseolus vulgaris, P. coccineus, Fi, F 2, Fa, and reciprocal Fl backcrosses reveals monomorphic and .polymorphic forms of leucine aminopeptidase (LAP) in the genus. The polymorphic forms (LAP-II) are controlled by the codorninant alleles, Lap-IIand Lap-Ll», Reciprocal backcrosses to both species show a highly significant deviation from the expected 1: 1 ratio when the donor parent allele is transmitted through male gametes. There is not a significant deviation from the expected ratio when transmission is through, female gametes. Differential gametic selection in conjunction with differential sterility suggests structural differences exist between the genomes of these species. America and from North America have been crossed artificially. The resulting hybrids are usually intermediate in morphology but differ greatly in fertility. There is no strong correlation between morphological similarity and the degree of fertility. There is, however, a strong correlation between polyploid level and fertility: the hexaploid X hexaploid crosses are considerably more fertile than the diploid X diploid crosses. The cytological, evolutionary and taxonomic implications of this work will be discussed.

Yang. Julie T., and B. L. Turner. University of Texas, Austin-SYSTEMATIC IMPORT OF ISOENZYMES . IN THE LEMNAcEAE----'Eighty-eight collections of the Lemnaceae, including species belonging to the genera Spirodela (foul' species), Lemma (seven species), Wolffia (three species) and Wolffiella (three species), were examined by gel acrylamide disc electrophoresis for their glutamate dehydrogenase, malate dehydrogenase, lactate dehydrogenase and beta-esterase zyrnograms (i.e., isoenzyme patterns among these enzyme systems). These data were assembled from organisms grown axenically under uniform cultural conditions. The zymograms were found to consist of major and minor isoenzyme bands; the former being relatively consistent among the various clones of anyone taxon; the latter were often variable but nonetheless diagnostic. Nearl;y all of the isoenzyme systems showed polymorphism WIthin the various species, except for glutamate dehydrogenase. This enzyme was nearly always present as a single band, but the Rp of the enzyme varied among the taxon from a low of 16 to a high of 32. Systematic implications of these data were mostly confined to the recognition of specific isoenzyme pattern for a given taxon; that is, each of the species could be recognized by the various zymograms in combination. In a few cases these data suggested that some redisposition of certain species among the genera might be made. Thus, the GDH, MDH and LDH zymograms suggested that Spirodela oligorhiza was related to Lemma through the species L. gibba and L. obscura. It was concluded that while isoenzyme information of this type might prove useful at the specific level, especially for purposes of identification and/or populational study, it was unlikely to prove useful in the evaluation of relationships above the generic level. 'OR THE SMALL COLLEGE CLASSROOM-Special problems arise in the use of the audio-tutorial method of instruction in small colleges with limited personnel and facilities. Problems concerning preparation of materials, supervision of study sessions, construction of special facilities, maintenance of equipment, and assignment of teacher load for this pilot project are described and approaches to solutions are discussed. Versatility of the technique in the local situation, student response, and anticipated modifications are described.

Anway, J. C. Ohio University, Athens-A LABORATORY EXERCISE ON THE DISTINCTION BETWEEN CLASSIFICATION, IDENTIFICATION AND RECOGNITION-The distinction of classification, identification, and recognition in an introductory taxonomy course is often difficult for the student to learn. A laboratory exercise for this level consistent with the modern trend of dynamic approach and student participation has been devised and tested. The primary aims of the exercise are to acquaint the students with: (1) variation in nature and the importance of an adequate sample; (2) the kinds of classification systems;

(3) the eonstruction of a key to deal with the classitication; (4) the necessity of names; (5) the distinction between identification and classification; (6) illustration of recognition. The students are given a highly varied assortment of woody fruits collected in the U.S.A. and Australia. They are told to classify them, name them, and set up a key. Each step is followed by a group discussion. An unknown is then presented for identification using their key. They are then given a chance to recognize an unknown Without the use of their key. Finally, a completely different unknown (not part of the origmal sample) is presented for identification, to illustrate the repercussions of an inadequate sample.

Bowen, W. R. Western Illinoiaj.University, Macomb-AN AUTO-TUTORIAL APPROACH TO TEACHING BIOLOGy-There is a common tendency in today's biologyteaching practices to forsake the laboratory where large masses of students are concerned. Yet the student will come face to face with the ideas of biology only in the laboratory and/or the field. Lectures, texts, etc., therefore become an adjunct to the overall understanding. An experimental auto-tutorial program was developed in an effort to provide a meaningful laboratory for the masses. An open laboratory session was structured as an independent study program. Written materials which integrated basic textual information with pertinent do-ityourself laboratory experimentation was utilized. The experimental work incorporated as much a "learn through doing' philosop,hy as possible. The overall program was an "in depth' analysis of basic concepts in biology. Lectures, discussions, and supplemental reading secondarily completed the program. A major impetus for the independent study was provided in the form of weekly evaluations (examinations). Major and non-major student response to this type of program will be discussed.

Martens, J. L. Illinois State University, Normal-ANoTHER LOOK AT GINKGO BILoBA-Ginkgo biloba L. is used in many classrooms and the following suggestions may be useful. During anthesis a challenge to both teacher and students is the successful addition of pollen to the micropylar exudate. A significant follow-up is a discussion on the desirability of growing trees of both sexes and the importance of planting the seed-bearing tree away from walks and driveways. A comparison of the young leaves with the pinnules of Adiantum illustrates the origin of a common name and serves to initiate a discussion on phylogeny and "mimicry." Logical is a reminder of Ginkgo Petrified Forest, a state park, near Vantage, Wash. A study of fallen seeds shows an increase in size of embryos as the seeds mature, and the occasional absence of an embryo provides opportunity for discussion and stimulates investigations. Aged seeds from which the fleshy outer layer of the seed coat has been removed are nut-like. When opened they illustrate the inner layer of the seed eoat as it adheres to the sclerenchymatous middle layer. The nucellar cap, in part, adheres to the now brittle megagametophyte. Soaking undamaged seeds in water for 24 hr demonstrates their hygroscopic nature and prepares the megagametophyte for sectioning and reserve food tests. The embryo is easily observed. A comparative study of the cross sections of stems of normal growth with those of dwarf branches adds another interesting area of study.

Martens, J. L. Illinois State University, Normal-EXPERIENCES WITH EVENING POLLINATION IN ZEA-8everal different lines of Zea were self-pollinated and cross-pollinated between 6:00 and 9:00 PM, central daylight time, during the 1965, 1966, and 1967 growing seasons. The resultant ears compared favorably with those resulting from late morning and early afternoon pollinations. Evening pollinations provided an opportunity to perpetuate inbred lines and build hybrids, when other duties or commitments interfered between 9:00 AM and 4:00 PM, the usual hours for controlled hand-pollination. Less possibility of contamination by unwanted pollen was an added advantage of working at this time. Carriers of Ii 0, Iw., and lW2 genes for chlorophyll deficiency in Zea are examples of lines that were selfed during these hours with good results. Also at this time of day crosses were made that were necessary to build lines which carried two and three different genes for "albinism" in Zea. The multiple lines (plants which carry two or more different genes for chlorophyll deficiency) exhibited heterosis and when selfed in the evening likewise produced wellfilled average to large ears. Lines with two genes segregated the ratio of nine green to seven chlorophyll deficient, and lines with three genes "threw" 27 green to 37 chlorophyll deficient.

Drum, R. W. University of Massachusetts, Amherst-INTEGRATED MIXED; MEDIA PRESENTATION OF GENERAL BOTANY FOR NON-SCNCE MAJORS-When nonscience majors are separated; from science majors into special lecture sections for General Botany, better organization of material and student interest in contemporary botanical research are greatly enhanced by judicious use of background music', olfactory-stimulation, dim lighting, and silent movies shown simultaneously with projection slides. The various media are used to increase a lecturer's effectiveness rather than offer a substitute for professional excellence. Human beings can learn while being entertained if the entertainment vehieles encourage emotional, personal involvement with the material being presented and do not distract or otherwise interfere. As non-science majors often seem hostile towards science curricula, an effort is made to utilize all available means for presenting General Botany in such an exciting and relevant manner that almost anyone could become interested in plants. This type of presentation is most satisfactory with student audiences of 100-1000 in auditoria equipped with modern light and sound equipment, and it is in part an attempt to overcome the empty magnification phenomenon which accompanies many poorly attended general background courses in large universities. Some selected mixed media for General Botany will be presented.

Hodson, Margaret. Marion College, Marion, Indiana-A GENERAL H1OI.OGY CL.\SS PROJEC'f IN PLANT ECOLOGy-In early spring 10 m X 10 m plots varying in terrain and development were set up in a wooded tract. Each laboratory section was divided into small groups. After a quick survey of the tracts, each group chose two plots to study and compare. At subsequent visits the groups filled out study sheets of their two plots, including physical and biological factors and a list of plants, using a SImple key to identify the flowers. At least four laboratory meetings were devoted to the study. Each student then presented a written report based on the study. The report included a discussion of the variations found in the plots as they were compared.

Business Meeting of the Section. metaphase in pollen tubes shows six chromosomes each with an individuality emphasizing homology. Therefore, the reduction from 12 to 6 involves more than numerical change as exemplified by the presence of only one homologous chromosome of each pair within a given pollen tube. The location of the centromere and the large chromosomes make identification possible. 10: -5 Vuksic, Vlatko, and Helena A. Miller. University of Pittsburgh and Duquesne University, Pittsburgh-DEVELOPMENTAL PATTERN OF SHOOT APICES OF WHE,\T PLANTS GROWN AT CERTAIN CONTROLI,ED CON-DITIONS OF LIIHIT AND TEMPERATURE-An experiment to test the effects of specific environmental conditions (low temperature and photoperiod) on developmental expressions of shoot apices of genetically identical wheat plants was devised and tested. It was found that unvernalized (not treated with low temperature) shoot apices of wheat plants remained in the vegetative stage and never flowered under the condition of short-day photoperiod (8 hr). However, the vernalized (low-temperature-treated) shoot apices of wheat plants grown under the long-day photoperiod (16 hr or longer) passed from the vegetative into the reproductive stage and produced flowers throughout the life of the plant. The methods and techniques used during this experiment were relatively simple and can be adapted easily for a laboratory exercise in any introductory botany course. Throughout the semester students should make their own observations of the apices of wheat plants grown under these various environmental conditions. They can gain experience in observing morphogenetic changes and recording them, particularly those related to floral initiation and differentiation. Their findings should also help them to understand the significance of the terms winter wheat and spring wheat.

u.ss Sharp, A. J. University of Tennessee, Knoxville-s-Tna IMPORTANCE OF ORGANISMAL AND ENVIRON-MENTAL BOTANY TO THE GENERAL STUDENT-Many of the decisions that the politician, the banker, the business man, the housewife, and most other citizens are called upon to tnake demand some knowledge of plants as organisms 'and of their relationships to the environment, In view of the complexity of the biological problems being created by. .inereased industrialization, urbanization, and other teclinblogieal destruction, it is hazardous to deprive any studen] of an adeqnate knowledge of plants as biological units and of their role in our environment and our social economy. procedures~l'e designed to emphasize the segregationalgenetic sigllilieanc,e of meiosis, rather than mere numerical reduction; sil commonly used to describe this process. Root tip, ,mllen mother cells, and pollen-tube cultures of Tradescantiti poludosa are used for the microscope-slide preparations, Colchicine-metaphases of root tips show 12 chromosomes represented by two sets. The meiotic metaphasea consist of six pairs. Finally, the colchicine-

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