FOR TEACHERS TO ACCOMPANY ELEMENTARY BIOLOGY " v GRUENBERG GIFT OF Agricultural Educ.Div. THWF n- BIOLOGY LIBRARY G MANUAL OF SUGGESTIONS FOR TEACHERS TO ACCOMPANY "ELEMENTARY BIOLOGY" BY BENJAMIN C. GRUENBERG n > > n , } '. v GINN AND COMPANY BOSTON NEW YORK CHICAGO LONDON ATLANTA DALLAS COLUMBUS SAN FRANCISCO BIOLOGY LIBRARY G MAIN LIKAKV.AUGGAR, Plant Physiology, chap. vi. XVI. THE LEAF AS STARCH FACTORY The concept leaf should include more than the familiar types. It is better to examine cursorily a large number of varieties than to study minutely a few forms. All the extremes afforded by the resources at hand from the rhubarb to the asparagus, from the cactus to the cedar, from the mullein to the tradescantia should be brought together until the student is quite convinced that the definition of leaf is not to be found in a description of a few or of many shapes. Examine with the microscope bits of epidermis peeled from any convenient leaves, and cross sections thin enough to show the tissues and if possible the stomata. Comparing the leaf to a factory, have students make diagrams showing the route followed by materials received from the air and from the stem until they are finally disposed of. To measure the transpiration of a potted plant, inclose the pot and earth in rubber sheeting and weigh the whole. Weigh MANUAL FOR TEACHERS 37 again at intervals and note the loss. For a qualitative demonstra- tion, the prepared potted plant may be placed under a bell jar; the condensation of moisture on the glass will indicate loss of water from the plant surface. To show the pulling force of the transpiration current, insert the stalk of a healthy leaf in the end of a glass tube, and seal the joint with paraffin. Fill the tube with water and set over mercury. The rise of mercury in the tube is a measure of the mechanical equivalent of the transpiration from the leaf's surface. Special readings and reports on insectivorous leaves. References. ANDREWS, Practical Course, pp. 189-195; BERGEN and CALD- WELL, Practical Botany, pp. 13-15, 18-20, 385-389; BERGEN and DAVIS, Principles, pp. 88-96, 102-106 ; COULTER, Plant Life, pp. 234-241, 251-255 ; COULTER, BARNES, and COWLES, Textbook of Botany, pp. 521-530, 551-578, 385-388,616-620; DARWIN, Insectivorous Plants; DUGGAR, Plant Physi- ology, chap, v; OSTERHOUT, Experiments, pp. 173-181, 203-223. XVII. OUR DEPENDENCE UPON LEAVES AND CHLOROPHYL This is in part a repetition of the thought in XIV, The Chemical Cycle of Life, but from a somewhat different point of view. The attention is directed to the concrete materials that we actually use. Materials used in connection with the study of leaf forms and structure, and museum material, may be used here. Connect the study with the local market and industrial conditions. For the study of algae, there should be microscopic prepara- tions or good charts. Homemade charts that will serve adequately can be prepared with a little effort. This topic furnishes an excellent opportunity for a synthetic review. References. COULTER, Elementary Studies, pp. 378-383; SARGENT, Plants and their Uses, 36, 137. Yearbook of the United States Depart- ment of Agriculture, an variety, magnitude, and values of crops. XVIII. STARCH-MAKING AND DIGESTION Digestion of starch can be demonstrated by using a very thin starch paste, (a) with some takadiastase and () with some human saliva. Use large test tubes ; keep at room temperature or warmer. MANUAL FOR TEACHERS Demonstrate starch test with iodin on small portion drawn off at the beginning of the experiment. Draw off at intervals of five or six minutes and test again. When there is no more starch present, test portion from each test tube with Fehling solution. The disappearance of the starch and the appearance of the sugar (the absence of which may be demonstrated at the beginning of the experiment) indicate that something has happened to the starch which probably has something to do with the formation of sugar. It is well to test the diastase with Fehling solution at the beginning, since some commercial diastase contains reducing sub- stances. A more striking and otherwise more satis- factory demonstration consists of showing the formation of dif- fusible substances by the action of diastase and saliva. Place the thin starch paste with saliva in a celloidin bag (see p. 31 of Manual), and starch paste with diastase in an- other bag. A third bag (control) contains merely starch paste. The three bags are suspended in three jars or tumblers contain- ing clean water. After the expiration of fifteen minutes, withdraw some of the surrounding water and test with Fehling solution. Repeat from time to time until there is a positive reaction. Then put a few drops of iodin inside each bag. The bags containing saliva and diastase will have lost their starch and will have diffused sugar into the surrounding water ; the control shows no change. Corn grains that have been soaked in water overnight may be tested with Fehling solution (after being cut open, some length- wise and some crosswise). Allow some of the soaked grains to sprout, then cut them open and test them. The presence of sugar is due to the action of a diastase upon the starch. FIG. 8 MANUAL FOR TEACHERS 39 References. For the teacher : COULTER, BARNES, and COWLES, Textbook of Botany, pp. 397-402 ; DUGGAR, Plant Physiology, pp. 265-271, 277-278 ; GREEN, Vegetable Physiology, chap, xvi ; LOEB, Dynamics of Living Matter, lect. ii. For the pupils: ANDREWS, Practical Course, pp. 6-10; BERGEN and CALDWELL, Practical Botany, pp. 144-146; COULTER, Plant Life, pp. 350-352; OSTERHOUT, Experiments, pp. 155-169. XIX. DIGESTIVE SYSTEM IN MAN If microscopic preparations of the tissues of the alimentary canal are available, students will be interested in examining them ; but they are not essential. Specimens of fresh materials obtained from the butcher may be shown to those who are not squeamish. None of the students would probably object to examining sausage casing that has been allowed to soak in water until soft. A satisfactory demonstration of peristalsis consists of placing a marble in a long piece of sausage casing and driving it through to the other end by pulling the casing through the fingers (see Fig. 8). Ordinarily it is not worth while to demonstrate the action of the various digestive ferments of the alimentary canal. If the notion of digestion or fermentation is clear, it is sufficient to show speci- mens of pepsin, peptone, pancreatin, ox-gall, etc. A good way to summarize this study is to have students make a simple diagram representing the alimentary canal, and to label it with the names of the organs on one side of the drawing, and the names of the processes involved on the opposite side. Have students prepare a table like the one below, and fill in all the blanks : THE ACTION OF DIGESTIVE JUICES ON FOODS ACTIVE JUICES FOODS DIGESTED RESULT OF ACTION Mouth .... Stomach . . . Intestines . . . Another form of summary is to have students describe the fate of an imaginary mouthful of food containing all the nutrients, in its course from the mouth to the large intestine. 40 MANUAL FOR TEACHERS References. HOUGH and SEDGWICK, The Human Mechanism, chap, viii ; STILES, Human Physiology, chaps, xiii-xv; STILES, Nutritional Physiology, chaps, xiv-xvi. Have pupils make special reports on digestive systems and on special organs of various vertebrate and invertebrate types or groups. XX. HEALTH AND FOOD STANDARDS It is important to establish a clear distinction between stand- ards that represent customs or usage, and norms established as the result of experiment or measurement. Have students present examples of usage among certain people who have remained be- hind the best thought and knowledge of the same or other com- munities. Get them to think of the reasons for this, and of methods for accelerating the standardization of practice. Get examples of food fads or other standard usages, with the principles offered in justification. Determining units for measurement ; get examples of as many kinds as the students happen to know. As a demonstration, deter- mine the time needed to raise a quantity of water to the boiling point in a given vessel, with the burner in use ; compare with results when using double quantity of water. Or use similar quantities with different size of flame. Explain principle of calorimeter ; if there is one in town, arrange to visit with the class and have its workings demonstrated. Study cases in which standards have come into general use after scientific determination. In the matter of food standards, bring out the principle of indi- vidual variation. This should be referred to as occasion offers, as one of the fundamentals of modern thinking about organic and social problems. To give the daily requirements more concrete significance, have the students calculate the mechanical equivalent of the energy represented by the daily ration. For example, compare the energy consumed by the organism in one day with the moving of a ton of freight, with the raising of passengers in an elevator a given .height, with the lifting of a quantity of ore or bricks, and so on. MANUAL FOR TEACHERS 41 The mechanical equivalent of one calorie is about 3,060 foot- pounds. One horse-power is 550 foot-pounds per second. References. HOUGH and SEDGWICK, Human Mechanism, pp. 211-217; ROSE,- Feeding the Family, chap. i. The teacher should constantly consult publications of research laboratories, such as those of Mendel, Lusk, Chittenden, Benedict, etc. See United States Bureau of Standards, Circular No, 55. XXI. FOOD REQUIREMENTS Have each student prepare a schedule of one meal, or of a day's meals, and then go through the calculations according to the methods used in the text. After the calculations are finished, have the food assortments of specimen charts criticized by the various standards. Have students formulate their own suggestions for the improvement of their diet, as, eat less ; eat less fat or protein ; eat more vegetables ; and so on. References. FISHER and FISK, How to Live, pp. 28-35; HOUGH and SEDGWICK, Human Mechanism, pp. 217-233; LEE, ROGER I., Health and Disease, pp. 31-45; ROSE, Feeding the F'amily, chap, iii ; STILES, Human Physiology, chap. xxv. Current publications. Have special reports made on rations for soldiers or for various institutional groups. XXII. FOOD AND DIETARIES It would be interesting and illuminating to collect examples of superstitions, folklore, and family traditions on what to eat and what to avoid. Misleading suggestions on the choice of food are frequently found in advertisements of special food preparations, and in more dogmatic forms. Many obscure pathological conditions have come to be recognized in recent years as due to disturbances in nutrition that may be corrected through proper adjustment of the diet. The students should be encouraged to note and report experiences and observations bearing on these points. Where there is an opportunity to correlate the study of food with the domestic-science work of the school, this should not be overlooked. In the study of food economy there is an opportunity for a great deal of practical work, and this is readily correlated with the domestic science. Using Fisher's tables, have students obtain MANUAL FOR TEACHERS current prices of the various foods, and calculate the cost of stand- ard (100 calorie) portions. An interesting piece of outside work consists of preparing a series of bottles or specimen jars showing the standard quantity of each of a series of food articles, together with the price of each. A parallel series might be prepared by an- other group of students, showing the quantity of each kind of food that may be obtained for a given amount of money, say ten cents or five cents. The labels on these jars should contain, of course, all the significant data, as in the two labels below : SERIES A TEN CENTS' WORTH OF CORN MEAL Quantity . Calories Protein Prepared by Date SERIES B 100 CALORIES OK OYSTERS Quantity . Protein Cost . . Prepared by Date Dry food materials need merely to be sealed in the jars or bottles. Meats, fish, fresh vegetables, etc. can be preserved in 4 per cent formalin solution. Each student need prepare but one or two specimens; and the information gathered is exchanged by comparison of costs and other data. The specimens may be kept indefinitely, and the collection may grow from year to year. References. FISHER and FISK, How to Live, pp. 35-40; HOUGH and SEDGWICK, Human Mechanism, pp. 233-243 ; JORDAN, E. O., Food Poison- ing, chap. ix. LEE, Health and Disease, pp. 54-68, 46-51 ; RAPEER, Edu- cational Hygiene, pp. 68-77. Special readings in ROSE, Feeding the Family. Have students compare special rations established for domestic animals, from reports of agricultural experiment stations and from the United States Bureau of Animal Industry. Current matter on vitaminesand on deficiency diseases. See XX. MANUAL FOR TEACHERS 43 XXIII. FOOD HABITS The practical value of these studies should of course issue in habits, habits of attitude as well as habits of conduct. It is, how- ever, extremely difficult to gauge the extent to which the studies have influenced the habits of the pupils. With discretion a teacher may from time to time put forth a question or a suggestion that will bring an illuminating reaction on this problem. For a study of the teeth, it is usually easy to obtain instructive specimens from a dentist. Cross and longitudinal sections may be prepared by means of a grindstone. But it is easy to spend too much time on the study of tooth structure and form ; these are not worth much unless it is desired to make a fuller study of compara- tive morphology of mammalian teeth. The important facts are few and quickly grasped, and are related to decay. A striking demonstration of the danger of exposing the teeth to rapid alternation of temperature consists of heating a test tube and then casually dipping it into a jar of cold water. It has been found very instructive to make a census of the proprietary drugs on sale or advertised in the neighborhood, for the purpose of determining the proportions of those offered as remedies for headaches and constipation. Labels or wrappers from such preparations make an interesting exhibit. References. FISHER and FISK, How to Live, pp. 44-51, 51-57? 78-89; HOUGH and SEDGWICK, Human Mechanism, chap, xix ; LEE, Health and Disease, pp. 51-53; ROSE, Feeding the Family, chap, ii; STILES, Human Physiology, chap, xxvi ; STILES, Nutritional Physiology, chaps, xxii, xxiii. Special readings in JORDAN, Principles of Nutrition, and in SHERMAN, Chemistry of Food and Nutrition. Teacher should be familiar with work of Cannon and of Carlson. See CANNON, Bodily Changes in Pain, Hunger, Fear, and Rage, chap. i. XXIV. THE SOCIAL SIDE OF THE FOOD PROBLEM Have the students find out the local situation in regard to the protection of the water supply, and classify the functions involved in this protection in order to see how much depends upon biological principles. 44 MANUAL FOR TEACHERS Have the students obtain copies of local regulations concerning food standards, food protection, and food sales. Reports of the state and municipal departments of health, bureaus of weights and measures, milk committees, etc. should be consulted. Collect labels from various food packages, showing the publica- tion of facts concerning preservatives, artificial coloring, etc., in accordance with specified laws, or of claims as to purity of materials used. It is impossible to know ordinarily the extent to which food is " faked." But reports are constantly appearing that throw light on this question, and students should know both how to obtain the information contained in such reports and how to interpret it. For example, the New Hampshire Board of Health issued one report in which it appeared that of three hundred and sixty-three samples of food taken in the market, nearly one half (164 45.2 per cent) were adulterated. Changes in the attitude of official and semiofficial bodies toward this matter are constantly being made, and students should know how to keep in touch with such changes. For example, in New York City the Board of Health began in 1914 to publish every week the names of all dealers or manufacturers convicted of selling foods not in accord with offi- cial standards. The plan of publishing names and addresses of violators has been especially valuable in connection with the milk business, since the ordinary milk buyers are practically helpless in their dealings with unscrupulous sellers. Newspaper clippings should be pasted in notebooks or posted on the class bulletin. Have students report on conditions in stores and markets where food is sold. After comparing notes in class, have them draw up a scale for scoring or grading the shops. Have students report on conditions in workshops, stores, fac- tories, and offices, in relation to lunch-rooms, opportunity for wash- ing up, etc. Much of this information can be obtained by inquiry among relatives and acquaintances. Where there is a school lunch service, it should be possible to cooperate for the purpose of establishing in the minds of the pupils standards in regard to conditions as well as in regard to the food, balanced rations, quantities, etc. Have students prepare schedules MANUAL FOR TEACHERS 45 of food values for the various items served in the lunch-room, and arrange to have the figures used in connection with the menus. If this is already the practice, sample menus may be used as basis for discussion of balanced rations etc. Where there is time, it is worth while to devote a whole period to the subject of National Food Resources. Begin with a compari- son of the proportion of the population engaged in farming at the close of the Civil War with the proportion so engaged at the time of the last census. Then compare the per capita production of various food materials at the two periods ; compare the yield per acre under cultivation, and so on. The point to be brought out is the increased control and the increased resources through the application of biological and other exact knowledge. Assign indi- vidual students to report on the various governmental activities related to the food yield that are mentioned in the text. Bring out the realization that the problem of food conservation means more than adequate production ; it involves matters of transporta- tion, marketing, storage and preservation, and, finally, adequate distribution in the economic sense, that is, the ultimate consump- tion of the food in a way that will contribute the utmost to the welfare of the nation or the community. References. HOUGH and SEDGWICK, Human Mechanism, pp. 505-514; JORDAN, Food Poisons, chaps, v, vi, viii ; LEE, Health and Disease, pp. 69-73. Special reports on war food administration ; on local and state regulations of food production, food distribution, and food standards ; on current studies pertaining to character and extent of malnutrition among children or other groups ; on current or local efforts to remedy defects of nutrition in large groups. Material can be obtained from the departments of health, commerce, and agriculture, and from the United States Children's Bureau. XXV. STIMULANTS, NARCOTICS, AND POISONS In getting the idea of acclimatization, the students will be led to draw upon their own experiences and observations. The point to emphasize is that the modified organism becomes dependent upon the new environment. Whether it works as well under 46 MANUAL FOR TEACHERS the new conditions as it can under the natural conditions is a different question, although an important one. The difficulty that many students have in forming chemical con- cepts may in part be met by the use of mechanical analogies, which are more readily visualized. For example, in thinking about the action of drugs or chemicals upon protoplasm, compare this action to the effects that may arise from introducing a foreign body into a piece of machinery. If a boy should stick his finger into the business region of a buzz-saw, the machine would keep right on working as though nothing had happened ; this corresponds to an indifferent chemical body, or to a " subliminal dose." If the boy should drop a bar of iron in among the wheels, it might catch be- tween the spokes and stop the machinery altogether; or it might catch against a moving part, simply slowing up the machinery. This corresponds to a narcotic, up to the " lethal dose." Finally, he could push his bar of iron against the belt connected with the governor of the engine and disconnect this part ; in that case the engine might suddenly begin racing at increased speed. This would correspond to the effect of a stimulant, or accelerator. References. FISHER and FISK, How to Live, pp. 64-78, 250-268 ; HOUGH and SEDGWICK, Human Mechanism, pp. 357-363 ; LEE, Health and Disease, pp. 125-134; "The Great American Fraud" (American Medical Association) ; Farmers' Bulletin, " Habit- Forming Drugs." / XXVI. ALCOHOL AND HEALTH - XXVII. ALCOHOL AND SOCIETY We must be on our guard against the temptation to resort to the hortatory method in dealing with this subject ; it is necessary to maintain a more calm and more tolerant spirit than that which characterized the campaigners of a generation or two ago. It happens altogether too frequently that intelligent, honest, and likable people are also alcohol drinkers. The awful things predi- cated about drinkers in the older books do not find confirmation in the daily experience of the students. Instead of discrediting the drinkers, these experiences discredit the books and the whole tribe of physiology and hygiene teachers. MANUAL FOR TEACHERS 47 There are available verified and verifiable data that help to demonstrate the undesirability of alcohol as a beverage, but these data are to be used in a common-sense way. We must avoid the fallacy of arguing from statistical generalizations to individual application. It is impossible to say " You will suffer " so and so if you drink. The very most that we can say is, " If you drink, your chances of becoming sick are increased by so many per cent ; and when you are sick, your chances of recovery are reduced by so many per cent." In other words, the data show simply group effects. We may therefore teach only that a society, or community, or class of people stands to gain by adopting this or that course of conduct. Our problem is to socialize the interest and make the individual resolve that, so far as he is concerned, the group of which he is a member is to profit from his learning. So long as our health teaching in regard to alcohol (and in regard to many other matters) was based on the sentiment of competitive advantages for the individual, it resulted simply in placing before the child the betting odds against the practices condemned. And since most children are fairly good " sports," the teaching did not suc- ceed in intimidating them. The individual can often afford to take chances ; the only certainty we can teach from our statistical studies is that the group suffers from the use of alcohol. To demonstrate the effect of alcohol upon proteins, add alcohol to the raw white of an egg ; this is a suggestion of how alcohol may injure protoplasm. Supplement with parallel demonstration of the coagulating effect of mercuric bichlorid solution and other " poisons." The point is to show that alcohol is one of a class of substances that are unquestioned poisons, and not something unique in its relation to protoplasm. Have students gather data on usages of local employers, in selecting workers for responsible positions, in the matter of drink- ing. Have them get information as to regulation of the patent- medicine trade by local or general authorities. Have reports made on fraudulent cures for alcoholism. What are the current and local developments in meeting the social requirements of the human animal that had been left to the exploitation of the alcohol 48 MANUAL FOR TEACHERS interests in the past ? Agitation and legislation since the entrance of the country upon the war. The soldier and alcohol. Opportuni- ties for special reports and studies are almost limitless. References. For the teacher: BILLINGS, Physiological Aspects of the Liquor Problem ; KOREN, Alcohol and Society. For the pupils : FISHER and FISK, How to Live, pp. 227-250; HOUGH and SEDGWICK, Human Mechanism, pp. 363-379; LEE, Health and Disease, pp. 113-125. An excellent condensed summary of all the significant data has been prepared by the D'Abernon-Newman Committee (British) under the title " Alcohol : its Action on the Human Organism." An American edition is issued by Longmans. XXVIII. AIR AND LIFE Review briefly the important ideas already learned on' the rela- tion of oxygen to energesis in burning. Have live plants and animals on hand for demonstration of breathing. If drawings have been made of cross sections of the leaf, refer to them and add further notes on the path of the air exchange involved in breathing. If there are no drawings and there is not time to make any, use wall charts, blackboard drawings, and microscopic demonstration. If the season permits, use live insects for the study of spiracles and breathing movements ; otherwise use prepared specimens. Study tracheae from microscopic mounts and from pictures and charts. Compare live earthworms with sandworms, bloodworms, or other gill-bearing worms near the coast. Use preserved speci- mens of mollusks and crustaceans for comparison of different types of gills. The course of the water in breathing is easily studied in crayfish and in fish. The breathing process in frogs should also be studied in the living specimens. The test of the students' grasp of the mechanism of breathing in the frog lies in their answer to the question, " What would happen to a frog that was forced to keep his mouth open indefinitely ? " Prepare in advance dissections showing the connection between the throat and the gill slits in the fish, and between the throat and the lungs in the frog. Some of the older students can make such MANUAL FOR TEACHERS 49 dissections under direction. Preserve good preparations in 4 per cent formalin for future use. References. BIGELOW, Applied Biology, pp. 502-503. Special reports on course of air (oxygen) in the breathing of various vertebrate and invertebrate types, from descriptions in available books on zoology XXIX. BREATHING IN MAN Obtain lungs of calf, sheep, or ox from a butcher. Use models of lungs, showing diagrammati- cally some of the detail structure. For making clear the mechanics of the diaphragm action, the appa- ratus pictured in Fig. 9 should be set up in advance. If there is a skeleton in the school, show the relation of rib curvature and rib movements to the expansion and contraction of the chest cavity. Have students study the move- ments of the chest and abdomi- nal wall with the hands while breathing slowly. Students, es- pecially boys, are interested in comparing lung capacity. If an aspirator is available, or records from the physical-training de- partment, compare lung capacity with chest expansion. Compare the number of breaths taken by different members of the class in one minute ; individual variation ; variation in depth of breath- ing of different pupils at the same time and of the same pupils at different times. Compare the number of breaths per minute before and after some vigorous setting-up exercises in the laboratory. FIG. 9 A bell jar, closed at the bottom with rubber sheeting, and at the top with a two-holed stopper carrying (i) a Y-tube with two rubber balloons, and (2) a glass vent with a rubber tube closed by a pinchcock 50 MANUAL FOR TEACHERS Demonstrate by the pupils themselves relation of posture to chest expansion, breaths per minute, tidal air. Compare notes on the effects of a tight belt or corset and other features of the clothing. References. BIGELOW, Applied Biology, pp. 503-505 ; FISHER and FISK, How to Live, pp. 18-28; HOUGH and SEDGWICK, Human Mechanism, chap, x; STILES, Human Physiology, chap. xx. XXX. VENTILATION In speaking of ventilation standards, it is not enough to learn figures for cubic feet per hour and the like. Have students measure off from a corner of the room enough space to represent say one thousand cubic feet ; have them get an idea of the cubic capacity of the classroom, of the home living-room, of the bedroom, and so on. To show the meaning of relative humidity in relation to the work of the lungs, set up two bell jars (or inverted battery jars), suspending in each a piece of wet filter paper. Under jar A place a dish of water; under jar B, an empty dish. Note the time in which the papers become dry ; that in A may remain moist for weeks. Compare the drying of clothes on a clear day and on a muggy day. Introduce the wet-bulb thermometer and show how differences between wet-bulb and dry-bulb readings are to be interpreted. Compare the lower temperature of the wet bulb with the feeling of a wet spot on the skin. Make clear how perspiration helps to regulate the body temperature. Use the illustration of the Australian water bottle. Have students report on standardized usage in mines, where low oxygen pressure is maintained to prevent explosions. Establish committees of students to be responsible for the ventilation and temperature of the classroom. References. FISHER and FISK, How to Live, pp. 7-14; HOUGH and SEDGWICK, Human Mechanism, chap, xxviii ; LEE, Health and Disease, pp. 74-83. Reports of current investigations, especially on ventilation in industrial establishments. MANUAL FOR TEACHERS 51 XXXI. CONTAMINATED AIR The dusty trades of the neighborhood or of the community, and those that yield injurious vapors or fumes, should receive special attention. Have students find out what these industries are and what conditions prevail for the safeguarding of the health of the workers. Are there any regulations or difficulties about the con- tamination of the community's air by smoke or fumes ? In the study of the effects of tobacco, keep in mind the limita- tions of the statistical method, as suggested in the notes on Chapters XXVI and XXVII, and the further sources of error that come from the possibility of the tobacco habit being in itself largely a selec- tive agent, as suggested in the text. In a school containing large numbers of boys it may be possible to collect data as to smok- ing and non-smoking, and to correlate these with physical and scholastic records. The data from your own school, or from a school in your own city or state, will carry more weight than those from some remote institution. Note especially the current and local sentiment and tendencies. References. HOUGH and SEDGWICK, Human Mechanism, pp. 377-379; Bulletin 231, United States Bureau of Labor Statistics ; Report of Y. M. C. A. committee on experimental study of the effects of smoking. XXXII. FIRST AID AND HYGIENE IN RELATION TO BREATHING Time the period during which members of the class can hold the breath. See whether those with unusually high records have any special technique that enables them to exceed the performance of the others. Artificial respiration, by the Schaefer or by the Silvester method, should be demonstrated and practiced by the members of the class on each other. If there is an emergency hospital, a life-saving station, a fire-house, or other similar institution within reach, arrangements should be made for the demonstration of a pulmotor 52 MANUAL FOR TEACHERS or other like device for the establishment of normal respiration after asphyxiation, drowning, or electric shock. In summarizing, make an attempt to get a survey of the prevailing habits of students and of prevailing home conditions with reference to these matters, as open-air sleeping, mouth breathing, and so on. References. Miners' 1 Circular No. j, United States Bureau of Mines ; Technical Papers Nos. 77 and 82, United States Bureau of Mines ; RAPEER, Educational Hygiene, chap, xv, " Open-Air and Open-Window Schools." XXXIII. TRANSFER OF MATERIALS IN PLANTS In anticipation of this study, place various kinds of twigs (pref- erably willow twigs) in jars of water to form roots. Three weeks or longer may be required. Girdling some of the twigs will enable you to make- clear the relation between the bark vessels (phloem) and the transfer of elaborated food in the stem. Have on hand microscopic preparations, especially of longitudinal sections of fibrovascular bundles. For the isolated bundles, use corn stalks or celery, either fresh or preserved in from 2 per cent to 3 per cent formalin. For explaining the exogenous type of structure and growth, get sections of various dicot or coniferous twigs, one inch or more in diameter. To show the distribution through the wood vessels (xylem) of stem and leaves, place seedlings, stalks of celery, or small succu- lent plants with roots, in tumblers containing dyed water (a few drops of red ink added to the water will do). In connection with the problem of the ascent of sap, recall the pull of the transpiration current and the demonstration of root pressure. If necessary, repeat. Get the idea of capillarity clear by means of glass tubes of various dimensions, including old thermom- eter tubes or the finest tubes you can get by drawing out a glass tube softened in a Bunsen flame. Place the tubes in pigmented water and compare the heights to which the fluid rises. Suggest the greater .capillarity of the microscopic vessels in the plant. In connection with the problem of the descent of sap, discuss thoroughly the behavior of girdled trees. Is the sap of the maple MANUAL FOR TEACHERS 53 obtained from the ascending or from the descending current ? What is the evidence ? Study commercial fibers (chiefly bast, such as flax, hemp, jute), bark fibers, etc. Correlate with commercial geography. References. For the teacher : COULTER, BARNES, and COWLES, Text- book of Botany, pp. 388-397, 678-696 ; DUGGAR, Plant Physiology, pp. 272- 273, 278-279. For the pupils: ANDREWS, Practical Course, pp. 112-118; BERGEN and DAVIS, Principles, chap, viii ; OSTERHOUT, Experiments, pp. 224-258. XXXIV. THE BLOOD Obtain blood from a butcher or from a slaughterhouse. Add a little formalin to prevent decomposition. Demonstrate clotting and the formation of serum by allowing the blood to stand quietly in a covered battery jar or beaker. Whip some blood in a battery jar with an egg-beater or a whisk of small twigs. The beating withdraws the fibrin from the blood as fast as it is formed. Allow some of this whipped blood to stand alongside the other ; when the clot is formed in the first, the second still remains fluid. Wash the corpuscles out of the clot with cold water ; show its fibrous structure and its protein composition, using nitric acid followed (after washing) with ammonia. Examine human blood under the microscope, placing a drop in a little salt solution. Pass oxygen through defibrinated blood contained in a tumbler ; pass carbon dioxid through another specimen. See pages 11-13 for the preparation of gases. Compare the lymph to the ocean as the medium of primordial life. Point out that certain types of bleeders suffer from the failure of the blood to form a clot, whereas in other cases the defect is in the texture of the capillaries. References. BIGELOW, Applied Biology, pp. 53-55, 482-486; HOUGH and SEDGWICK, Human Mechanism, pp. 132-135; STILES, Human Physiology, chap. xvi. 54 MANUAL FOR TEACHERS XXXV. THE CIRCULATION OF THE BLOOD Demonstrate the circulation of blood in the web of a frog's foot or in the tail of a tadpole. To keep the animal quiet while on the stage of the microscope, it may be chloroformed ; but you must be careful not to expose it too long to the fumes of the anesthetic. Place the frog in a battery jar in which is suspended a wad of cotton containing the chloroform, and cover. The low power of the microscope is sufficient Point out that the large pigment cells are not in the blood ; these cells are often confusing. Demonstrate the structure of a beef or calf heart ; get good models if these are available. Have students tabulate data as to the circulation and as to the changes that take place in the blood in various parts of its course. Note the exception to the rule that " blood goes from arteries to capil- laries and from capillaries to veins," namely, the portal circulation. References. HOUGH and SEDGWICK, Human Mechanism, pp. 136-149; STILES, Human Physiology, chaps, xvii, xviii. XXXVI. HYGIENE OF THE CIRCULATORY SYSTEM Have students find and count their pulses for a given time (as for one minute), and record. Have the class stand up and go through setting-up exercises, and then record the pulse again. If a stethoscope is available, have them listen to their own heartbeats and to any particularly interesting cases, as of mur- murs etc. Call attention to the evidence of danger in overtraining in athletics, for example, the experience of naval cadets in after life. Present a collection of antiseptics suitable for the treatment of wounds and scratches. Study bandages. Demonstrate methods for stopping bleeding, including nose- bleed. Demonstrate the use of the tourniquet. Study the use of astringents. Have students tabulate the results of their study, types of situations and treatment, appliances, etc. MANUAL FOR TEACHERS 55 Have students tabulate the factors that have an influence upon the condition of the blood, and the results of various derangements, as food, bowel habits, breathing, rest and fatigue, stimulants and narcotics, and so on. References. For the teacher : CANNON, Bodily Changes in Pain, Hunger, Fear, and Rage, chaps, iii, v, ix, x ; HOUGH and SEDGWICK, Human Mechanism, pp. 149-161; LEE, Health and Disease, chap, v; STILES, Human Physiology, chap. xix. XXXVII. THE BLOOD AS A LIVING TISSUE Review white corpuscles in terms of the properties and behavior of naked protoplasm, emphasizing especially types of irritability. Have on hand specimens of antitoxin, vaccine for typhoid and smallpox, and other serum preparations. Culture tubes and swabs for diphtheria cultures should be seen and handled, and their use demonstrated. The idea of a precipitate can be represented very easily : add some sulfate solution to a solution of barium chlorid. The subject is usually very interesting to young people, and leads to many questions. The teacher should be prepared to answer some of these concretely and specifically, as the dosage for antitoxin, the unit, and how it is determined ; the use of serum methods in diagnosis and in the specific identification of animal or other organic material ; the use of the opsonic index ; the diseases against which vaccination has been successfully used ; the arguments pro and con on compulsory vaccination ; the phenomena of anaphylaxis ; and so on. Get examples of individual variations in natural immunity and racial variation. Experience of students with acquired immunity, whether the result of disease or of special treatment ; data on the rela- tion of temperature, fatigue, nutritive conditions, etc. to immunity. The subject of heredity often obtrudes itself insistently and must be handled firmly. To differentiate between the inheritance of a disease and the inheritance of a natural susceptibility is not difficult if the specific relation between bacteria and disease has been first made clear. But when it is necessary to speak of a 56 MANUAL FOR TEACHERS possible infection of an infant within the body of the mother, many teachers balk and make trouble for themselves. Draw upon the local department of health and the hospitals for help. References. BUCHANAN, Household Bacteriology; HOUGH and SEDG- WICK, pp. 497-504. Special reports on the history of smallpox vaccina- tion ; on experience of the army with typhoid vaccination ; on the work of Behring, Metchnikoff, etc. XXXVIII. WASTES AND BY-PRODUCTS OF ORGANISMS Review chemical changes, with special emphasis upon the forma- tion of new substances. Cell metabolism involves the formation of new substances ; some of these are indifferent (water), some are useful (proteins), and some (carbon dioxid, urea, various acids) are injurious, at least in excessive quantities. Grow some young seedlings in a moist chamber or under wet paper, in contact with a polished piece of marble. The etching of the stone shows the action of some add, but chemical studies fail to reveal any organic acid secreted by the roots. The car- bon dioxid (respiration product) in the water is sufficient to dissolve the carbonate of lime. Guard against the teachings of some of the older books, which still point to the etching as indicating an adaptation for dissolving mineral matter. Some of the dissolved mineral may be absorbed by the roots, but the secretion is of the same character as our exhalation of carbon dioxid through the nose. Compare the accumulation of insoluble materials in the tissues of plants with the deposit of starch etc. in tubers and other storage organs. Microscopic demonstration of pigments ; chloroplasts as well as sap pigment may be found in the corolla of the pansy. Study museum specimens of tannin and its sources. Give a demonstration of tanning (as of white of egg) and of tannery products. Study specimens of other plant products, essential oils, alkaloids, acids, etc. Correlate with commercial geography. Microscopic demonstration of silica and raphides in plant cells : use scouring rush (Equisetum) for the former, and Indian turnip (Arisfzmd) for the latter. MANUAL FOR TEACHERS 57 Study the Paramecium again, with special attention to the con- tractile vacuole. Any other available protozoa would do as well. Cut kidney of calf or sheep lengthwise to show gross structure. Show microscopic preparations of kidney for gland structure. Microscopic sections of the skin are usually not satisfactory for those unskilled in the use of the microscope. A better idea of skin structure is to be obtained from a good model. References. COULTER, BARNES, and COWLES, Textbook of Botany, pp. 412-416, 620-626,718-725; HOUGH and SEDGWICK, Human Mechanism, pp. 177-186 ; SARGENT, Plants and their Uses, chaps, iv, v ; STILES, Human Physiology, chap, xxiii. XXXIX. HYGIENE OF EXCRETION What are the local and state regulations regarding the provision of drinking water in shops, factories, etc. ? What are the local usages in this respect, and as to public drinking fountains ? To what extent is there need for official regulation regarding the provision of adequate toilets and washing facilities in industrial and commercial establishments ? public comfort stations ? What are the public bathing facilities ? What are the tendencies as to home bathing ? How much water (and fluid with food) does each of us take in during the day ? Relation of physical exercise to circulation and excretion ; why perspiration is healthful. References. FISHER and FISK, How to Live, chap, iv; HOUGH and SEDGWICK, Human Mechanism, pp. 413-424; LEE, Health and Disease, chap. iv. XL. EXCRETION AND FATIGUE XLI. FATIGUE AND THE WORKER Use a dynamometer from the gymnasium, or a spring scale from the physics department, to explain the principle of the ergo- graph. Have a number of students make records at the beginning of the day and again at the close ; or get records of gymnasium per- formance, as "chinning," made at intervals involving work and rest. 58 MANUAL FOR TEACHERS Compare experiences with fatigue and endurance. Have students make special reports on the introduction of " scientific management," or " standard motions," in local indus- trial or commercial establishments, or on readings upon the sub- ject. Have special reports on the findings of the Health of Munitions Workers Commission. Collect data on hours, variations in work, pauses, and overtime in local establishments. What are the local or general regulations in these matters ? To what occupations do they apply ? What occupations are explicitly exempted ? Why this discrimination ? Get information on the distribution of accidents in industries during the day ; during the week ; during the year. Have students plot graphs and analyze on physiological grounds. Compare also records of school tests made with a view to measuring the influence of accumulating fatigue upon attention etc. Show how exercise of the large muscles helps to rest the sedentary worker by accelerating the blood flow and facilitating perspiration. References. CANNON, Bodily Changes in Pain etc., chaps, vi-viii; GOLDMARK, Fatigue and Efficiency ; HOUGH and' SEDGWICK, Human Mechanism, chap, v, pp. 314320; LEE, Health and Disease, chap. v. Bulletins and current reprints of the United States Public Health Service ; Bulletins of the United States Bureau of Labor Statistics. XLII. NERVES AND THE REACTIONS OF ORGANISMS Demonstrate some of the common reflexes by the students themselves. The knee-jerk is interesting and amusing when intro- duced for the first time, and it gives food for thought. Feed live worms to frogs in the laboratory, or use a dangling bit of red worsted. Have students report experiences in fishing, or with wild birds, or with domestic animals. Refer to the coughing reflex, and to sneezing and vomiting. Have students report their own observations and examples. The gland reflex that is most familiar is that of the mouth watering, but the cold sweat is perhaps not altogether strange (although this is not the same kind of reflex as the others mentioned). MANUAL FOR TEACHERS 59 Have prepared microscopic slides showing nerve structure. It is hardly worth while to study the muscle under the microscope. Under chloroform dissect out the long muscles of a frog's leg, with the associated nerve ; stimulate with the electric current from two battery cells. Show contraction in response to the stimulation of the nerve and in response to the direct stimulation of the muscle itself. The dependence of the muscle upon the nerve connections may be suggested, though not strictly demonstrated, by bending the middle finger forward until the tip is opposite the palm of the hand, as in Fig. 10. The nerve fibers connected with the muscles controlling the end segment are com- pressed and apparently inactive. The end joint may be moved about (by the other hand) and seems lifeless. Use a pithed frog or one in which the cord is severed back of the medulla, to demonstrate the persistence of useful re- flexes independently of the higher centers. Refer also to the chicken that runs around after the head is cut off. Have students suggest other examples. Recall the increase in pulse rate on FlG taking exercise, as an example of a reflex that does not shunt any impulses into the brain cortex. The increased heart work is due to a series of reflexes involving chemical stimulation (the partial pressure of carbon dioxid in the blood) and muscular reactions, but no conscious sensation and no voluntary influence upon the heart muscles or upon the breathing mechanism. Point out the fallacy of assuming that the reflexes, or the natural behavior, of organisms are necessarily adaptive. The feeding of nearly all animals depends upon reflexes, and the escape from enemies also involves reflexes. If the reflexes were perfect, the frog would catch every fly he tries to catch, and the fly would escape from every frog that tried to catch him ; the victim (food) would be assured to the feeder, and the safety of the prey would 60 MANUAL FOR TEACHERS be equally assured, and the feeder would starve. Have pupils find illustrations of the principle that some reflexes are indifferent, that some are even injurious, and that none are perfect as adaptations. References. For the pupils: HOLMES, Animal Biology, chap, xxiii; HOUGH and SEDGWICK, Human Mechanism, chaps, vii, xv. For the teacher: DONALDSON, Growth of the Brain; LOEB, Comparative Physiology of the Brain ; STILES, Human Physiology, chaps, vii, vi, viii, ix ; STILES, The Nervous System. XLIII. TROPISMS AND THE BEGINNINGS OF SENSE The idea of a general reaction is not so strange as it may at first appear. Recall that the child winks not only when something approaches the eye, but also when he hears a sudden, loud sound, or when he is startled. The flight of the bird may be initiated by many different stimuli; a worm contracts in response to many different stimuli ; the ameba shrinks into a spherical mass in response to many different stimuli ; and so on. Compare seeing stars when the head is struck. The students will no doubt brin^ further examples, once they get the idea. Experiments on the senses are always interesting and may be devised in endless variety. Have the students work in pairs. To get differences between various parts of the skin in respect to discrimination in touch, use compasses with the points close together and gradually opened apart, noting the smallest separation that can be distinguished as two points in the different parts of the skin tried, as the back of the hand, the neck, tips of fingers, tip of tongue, wrists, face, etc. For the hot and cold points, try series of points on the palm of the hand, guiding by the folds. Use bits of wire or nails about two inches long. Place nails in hot water (about 80 degrees C.) and some in cold water (about 5 degrees to 10 degrees C.). Change as soon as the temperature of the nail approaches that of the skin closely. Have the students try the hot and cold points on the cheeks. For experiments with taste, use dilute solutions of salt, sugar, acetic acid (vinegar), and very dilute solutions of quinine or aloes. MANUAL FOR TEACHERS 6 1 With a glass rod drawn to a very fine, rounded point (and rinsed clean after each use), have the students find and chart the distribution of the various papillae on the tongue. For showing the relation of odors to flavor, have various sub- stances (foods, spices, condiments) placed in the mouth of a blindfolded student, holding his nose to prevent the inhalation of vapors from the air or from the pharynx. Record the discrimi- nations made, either by naming the substances recognized or by describing them. Call attention to the danger of interpreting movements of organisms in terms of likes and dislikes in the absence of real knowledge about the emotions involved. Earlier natural philosophy of all peoples appears to take this form, and it is indeed difficult to think of energies except as attractions and repulsions ; but we may learn to use these terms without implying what usually goes with them when applied to human conduct. References. For the pupils: CLODD, The Childhood of the World, Part II ; HOLMES, Studies in Animal Behavior, chaps, i-v ; HOUGH and SEDGWICK, Human Mechanism, pp. 263-265. For the teacher: HOLMES, -Evolution of Animal Intelligence, chaps, iii, iv ; LOEB, Forced Movements ; LOEB, The Organism as a Whole, chap, x ; MORGAN, Evolution and Adap- tation, chap, xi ; WATSON, Behavior, chaps, i-iii. XLIV. EYES AND LIGHT It is not difficult to keep Euglena in the aquarium, and in suffi- cient quantities to show the collection of the organisms on the illuminated side and the reversal of the tropism on exposure to direct sunlight. The idea of reaction depending on physiological state should offer no serious difficulties. Compare the effect of seeing tempting food before a meal and after a meal. The mouth does not water so readily when one is replete. So, a tired boy is not aroused by temptations that would ordinarily lead him to great exertions ; when one is ill, he wants none of the amusements that ordinarily appeal to him ; and so on. The students can furnish abundant illustrations from their own experience. The point to keep clear is that the protoplasm can be modified in its conduct 62 MANUAL FOR TEACHERS by the presence or absence of various substances, by temperature, by light, and by other incident forces. Hydra and frogs are also valuable for showing the light tropisms and the influence of intensity. Earthworm habits are known to many boys. Assign for special report the behavior of earthworms under varying intensity of illumination; and the behavior of various water animals, including fishes. Compound eyes of insects or other arthropods should be examined ; have also microscopic preparations of eye surface and eye section. A good model of the human eye is almost essential for a satis- factory study of this topic, but good charts may be acceptable substitutes. A box camera that is readily taken apart will be of help ; get one that has a focusing screen of ground glass. Have the students study the pupil reflex with changing illumination, working in pairs. Rarely a person is found who can control the movement of the iris. It is probable that in most cases the control is indirect, the subject produces the movements by changing the focus while appearing to be staring fixedly, or he does so by imagining sudden changes from extreme light to extreme dark; or the reverse. This is in a way similar to making the mouth water by thinking of good things to eat. The students should finish this study with the conviction that many of the movements of organisms are quite as mechanical as those of a machine ; and they should be as ready to give up attributing to emotions the movements of animals as they would be to deny emotion to a phonograph reproducing sentimental ballads. In the case of the animals, as in that of the phonograph, the phenomena, including the emotions, are produced because the thing is built thus and so. References. For the pupils : HOUGH and SEDGWICK, Human Mechanism, pp. 244-258. For the teacher: HOLMES, Evolution of Animal Intelligence, chap, vii; STILES, Human Physiology, chap, xi ; WATSON, Behavior, chap. xi. For reversal of tropisms : LOEB, Forced Movements, chaps, v-xi, xii, xix. MANUAL FOR TEACHERS 63 XLV. HYGIENE OF THE EYES Where students' eyes are not regularly examined, arrange for examination with Snellen's test cards and with astigmatism charts. Make clear the fact that glare depends not upon the intensity of the high lights but upon the contrasts. Have students collect information about light conditions in local establishments, with reference to abundance and distribution of illumination, presence of flicker, glare, etc. Have students collect information about special dangers to eyes in local establishments, and about methods of guard- ing the eyes. Make a study of goggles used for special purposes. What are the local and state regulations concerning conditions inimical to people's eyes ? Are there any local regulations requiring the administration of silver nitrate to the eyes of the newborn ? Give statistical data as to the prevalence, increase, or decrease of blindness ; preventive and remedial measures. Demonstrate the administration of eye-drops and the use of the eye-cup. Show how a foreign body is to be removed. Demonstrate the proper and improper placing of reading, writ- ing, and other work in relation to illumination. Point out the objection to illumination of work by direct sunshine. References. For the pupils: HOUGH and SEDGWICK, Human Mecha- nism, pp. 395-401 ; LEE, Health and Disease, chap. vii. For the teacher: PYLE, Personal Hygiene, pp. 169-274. XLVI. SOUND SENSATIONS Have some students report on the methods used by physicists for determining the vibration rates for light and sound waves. Come to a common-sense conclusion as to the old paradox about there being no sound if there were no ears. Some experiments may be made on pitch discrimination ; and you may find one or two students who can recognize absolute pitch. Museum and demonstration specimens for various types of sound-perceiving organs. Note the lateral line in fishes, the eardrum in the cricket and locust, and so on. 64 MANUAL FOR TEACHERS Good models are essential for the study of ear structure, but good charts are helpful. It is not worth while, however, with most classes, to give much time to the detailed study of structure. References. For the pupils : HOUGH and SEDGWICK, Human Mechanism, pp. 258-262, 401-402 ; STILES, Human Physiology, pp. 143-148. For the teacher : WATSON, Behavior, chaps, xii, xiii. XLVII. RESPONSES TO GRAVITY Have students report on insects and other animals in which they may have had an opportunity to observe evidence of response to gravity, including balancing and righting movements. Demonstrate the idea of the statolith with a covered stender dish containing a cork. Show with blindfolded students that we are aware of our posture without seeing our environment. With the frog it is easy to demonstrate compensatory move- ments. Place the live frog in a glass jar. Tilt the jar so as to bring the animal's snout down, and reverse. Tilt laterally. Turn on vertical axis. If the movements are properly timed, the responses of the animal are immediate and striking. It is possible to show that these movements are due to semicircular canal reflexes by eliminating the function of the eyes, either by covering them with an opaque mixture of cotton, vaseline, and lampblack, or by cutting the optic nerves, or by surrounding the jar with a large piece of paper or cloth that offers no point for fixation. On the other hand, it may be shown that many of these responses arise from eye reflexes, by destroying the semicircular canals or by cutting the nerves leading from them. In that case, however, there remain disturbances in locomotion, showing that the animal depends upon the semicircular canals for its orientation in space. Have students make comparative tests of sensitiveness of hearing by determining the distances at which each may distinguish the tick- ing of a watch. The same watch will of course be used in all the tests. References. For the pupils : HOUGH and SEDGWICK, Human Mecha- nism, pp. 262-263. For the teacher : WATSON, Behavior, chap. xiv. There will be numerous reports and monographs on the testing of candidates for aerial service, giving results of investigations conducted during the war. MANUAL FOR TEACHERS 65 XLVIII. INSTINCTS Have students note examples of instincts in animals and in young children of their acquaintance, and then attempt to analyze these instincts, so far as possible, in terms of reflex chains. Note that instincts, like reflexes, cannot be perfect in the adaptive sense. Have students make note of variations in the manifestations of instincts brought about by changes in the physiological state or by the concurrence of two or more stimuli leading to more or less conflict between responses. Have students report experiences with animals, or from their own past, in which instincts were modified, either through the elimination of elements or through the formation of associations. All sorts of learning and unlearning, breaking and training, in animals and in very young children would furnish illustrations. References. For the pupils: DARWIN, Expression of the Emotions; DARWIN, Vegetable Mold and Earthworms ; FABRE, The Wonders of Instinct ; HOLMES, Studies in Animal Behavior, chaps, vi, xi. For the teacher: HOLMES, Evolution of Animal Intelligence, chaps, v, vi ; LOEB, Forced Movements, chap, xviii ; LOEB, Comparative Physiology of the Brain ; LOEB, The Organism as a Whole ; WATSON, Behavior, chaps, iv-v. XLIX. HABIT The study of habit should culminate in effective resolution. It is well to have clearly in mind the mechanism of habit formation, the association factor and the short-circuiting of impulses out of the cortex into the spinal cord ; but the important thing eventually is the habit of habit-control. Have students give striking examples of habit responses (often humorous) and of good and bad habits. Reports on experience in training lower animals ; on forming and breaking habits purpose- fully, from observations as well as from personal experience, from fiction and drama, and from history and biography or other casual reading. Get examples of inhibitions from students' experience and observation. 66 MANUAL FOR TEACHERS Study the relation of practice to habit formation and the measure- ment of practice effects, for example, the number of repetitions or the time required for mastering a movement (in athletics, in workmanship, in musical performance, etc.) ; the memorizing of poetry or lines in a play ; the mastery of mathematical processes, penmanship, drawing, and so on. Examples of arbitrary associa- tions or habits are found in learning the telegraph instrument and codes, in stenography, in typewriting, in cipher codes, and so on. Have students note examples of routineers among young persons, and of older people who are not routineers. Give examples of routine that could be replaced by other equally serviceable routine for the sake of gratuitous practice in changing habits, as shifting keys or money to another pocket, rearranging furniture at home, changing route to school, and so on. Consider the utility and the dangers of habits. References. JAMES, Psychology (Briefer Course), chap, x; HOLMES, Studies in Animal Behavior, chaps, vii-ix ; HOUGH and SEDGWICK, Human Mechanism, chap, xviii ; STILES, Human Physiology, chap. xii. For the teacher: HOLMES, Evolution of Animal Intelligence, chap, vii ; LOEB, Forced Movements, chap, xix ; WATSON, Behavior, chaps, vi-ix. L. CHEMICAL INJURY TO THE NERVOUS SYSTEM Have students report on the present status of regulatory laws pertaining to the manufacture, sale, advertising, and labeling of preparations containing alcohol and other habit-forming substances. A comparison of labels from patent medicines, headache cures, etc. is instructive. Have individual reports on special reading assignments. The subject of this chapter should not be dismissed without attention being called to the advantages that the race has derived from an understanding of the physiological effects of various alkaloids and synthetic compounds. A report on the contributions of anesthetics and alkaloids to surgery etc. is quite as important as one on the dangers of these substances. References. HOUGH and SEDGWICK, Human Mechanism, pp. 376-377 ; LEE, Health and Disease, pp. 128-132. In encyclopedias, articles on anesthetics. MANUAL FOR TEACHERS 6? II. UNITY OF LIFE This study should consist of a synthesis of all significant physio- logical ideas. Have students make lists of all the processes or activities that are common to several different organisms specified, the organisms selected representing diverse types and including plants as well as animals. For each process or activity, have students describe the behavior of the organism as a whole, and also the behavior of single cells of the organism. For each process or activity, have students compare the types of organisms selected ; that is, point out similarities and differences. For the organism as a whole, show the interdependence and coordination of processes; no part has meaning except in its relations to all the others. References. For the teacher: CANNON, Bodily Changes, chap, xiv; CRILE, Man an Adaptive Mechanism; LOEB, The Organism as a Whole, chaps, i, xii ; MORGAN, Evolution and Adaptation, chaps, i, iii, x. PART III. THE CONTINUITY OF LIFE LII. GROWTH AND REGENERATION The idea of the varying ratio of surface and volume can be made clear to many students by means of suitable diagrams ; but there are very many who find it extremely difficult, or even im- possible, to think in three dimensions from data supplied by figures in one plane ; that is, figures of two dimensions. These can be helped by the use of modeling clay. The clay is first cut into cubes of the same size, say one inch or one centimeter. The cubes are stacked up into a larger mass, and the superficial area determined. The mass is successively broken down, with the resulting increase in exposed surface made obvious. One-inch cubes of wood may be used. While the idea of the mathematical limits to the growth of a cell should be clear, it should not be emphasized to the point of excluding the idea of other factors operating in the limitation of growth. Current studies on the relations of internal secretions to the regulation of growth and form are constantly throwing new light on the subject. Have regenerated leaves, starfish and Crustacea with regener- ated limbs, specimens of knit chicken bones, etc. on hand for demonstration. In some of the larger cities it is possible to obtain from research laboratories or from museums specimens illustrating regeneration in vertebrates, mollusks, and other forms. Have students look out for examples of pollarded and grafted trees, and for newspaper accounts of skin and bone grafting, or trans- plantations of organs. Have specimens of grafts for demonstration. References. For the pupils : BERGEN and CALDWELL, Practical Botany, pp. 82-89 ; BERGEN and DAVIS, Principles of Botany, pp. 64-70; COULTER, BARNES, and COWLES, Textbook of Botany, pp. 417-426; DUGGAR, Plant Physiology, chap. xiii. For the teacher: DAVENPORT, Principles of Breed- ing, pp. 316-338 ; LOEB, The Organism as a Whole, chap, vii ; MORGAN, Experimental Zoology, chaps, xv-xxii. 68 MANUAL FOR TEACHERS 69 LIII. DEVELOPMENT In the spring it is possible to have live frogs' eggs in dishes, and to watch their development under the microscope and magnifying glasses. A series of models showing the development of Amphioxus (fifteen to twenty stages) is helpful. In the absence of models, charts may be used. Have preparations and models showing the development of different types of insects, a fish, a frog, a bird (chick), and a mammal (sheep or rabbit). Eggs and cocoons of various local insects, also mealworms and other insect larvae, should be examined alive. If possible, the emergence of the animals from the resting stage (egg or pupa) should be observed in the classroom by the students. In some localities it should be possible to visit incubators or henneries, to see the chicks come out of the shell. Along the shore, shedder crabs and the molting of many animals may be observed. Caterpillars in the process of pupation may be studied in the laboratory. From spring to late summer (from April to September for most parts of the country) it is possible to get complete life histories of mosquitoes by exposing tumblers of water on warm evenings ; the female mosquitoes will deposit their eggs, and the development may then be watched in the laboratory, under a reading glass. Cover the tumblers with cheesecloth, to prevent the escape of the adults. Under favorable conditions the development of the frog and the early stages of fishes can be followed in the laboratory. If possible, excursions to fisheries and to field should be made for the study of the stages in animal development. If goldfish are kept in the laboratory or stock-room, one can manage to get fresh segmentation stages late in the winter and in the early spring. The animals are fed up in the winter; at the beginning of the breeding season the fish are isolated in large battery jars, and then " stripped " into shallow glass vessels. Incubators for bacteriological work with thermostats can be used for the incubation of hens' eggs (104 F.). You must make 70 MANUAL FOR TEACHERS sure that the eggs are fertilized ; it is best to purchase from poultry specialists, and to examine them by holding up to light after three or four days. References. Special reports on life histories of various insects and batrachians; MITCHELL, CHALMERS, The Childhood of Animals, chap. ii. For the teacher : CONKLIN, Heredity and Environment in the Develop- ment of Man, chap, i, pp. 179-187 ; DAVENPORT, Principles of Breeding, chap, vii, pp. 336-344 ; KELLICOTT, General Embryology, chaps, i, ii. LIV. CONDITIONS FOR DEVELOPMENT It is very difficult for most people to separate in their minds the facts of growth from the facts of development. Call attention to diversities in size among the members of the class ; then have the students decide whether size is always and everywhere directly correlated with maturity ; that is,' whether growth (in size) has always been identical with or even parallel with development. Nevertheless, conditions that are unfavorable to growth are likely to be unfavorable to development ; ordinarily growth furnishes the material basis for development. For a comparison of different conditions, concentrations, etc., in relation to growth of yeast, use fermentation tubes (Fig. n). Instances of malnutrition reacting upon development are to be found in nearly every community. Malformations and monstrosi- ties of various kinds are referred to in books and in current litera- ture. Consider the effects of early neglect, of foot-binding, etc. References. For the teacher : AYRES, Laggards in our Schools, chap, xi ; DAVENPORT, Principles of Breeding, chap, ix ; MANGOLD, Problems of Child Welfare, Part I, chap, iii and Part II, chap, i ; MORGAN, Experimental Zoology, chaps, ii-iii. Publications of the United States Children's Bureau. LV. NEW ORGANISMS Show yeast cells under the microscope for the buds. Fresh material (in dilute molasses) is necessary. To show the spore formation, use preparations from an older culture ; that is, one from which the food has been exhausted, MANUAL FOR TEACHERS Have students make experiments on the distribution of mold and yeast spores. Thin slices of bread exposed under various conditions or in different localities (or directly inoculated with dust) and placed in moist chambers will serve as media for the molds. For moist chamber a tumbler inverted over a few thicknesses of wet filter-paper or blotter will do. For the yeasts, fruit juices or sirup diluted (a teaspoonful to the pint), or weak cider, exposed in test tubes, which are then closed with plugs of cotton. Study spores of molds under the micro- scope. Mildews, rusts, mosses, ferns, and other plants should be drawn upon for specimens of spores. Many kinds of spores, including pollen grains, can be made to germinate by placing them in a drop of dilute sugar solution on a microscopic slide in a moist chamber. Germinate fern and moss spores on moist earth under glass. Sporangia should also be seen. References. Special reports on spore for- mation etc. in various plants. HOLMES, Animal Biology, chap, xxvii; OSTERHOUT, Experi- ments with Plants, chap. ix. For the teacher : COULTER, BARNES, and COWLES, Textbook of Botany, pp. 805-816; PARKER and HASWELL, Zoology. FIG. n. Fermentation Tube Fill the tube completely with the nutritive fluid. Insert the yeast or culture into the low- est part of the bend, using a pipette. Close the mouth with cotton. The accumulation of gas in the highest part of the tube is both an indication and a measure of fermentation. The bulb should be only partially filled, to leave space for the liquid displaced from the tube LVI. SEX Favorable paramecium cultures show conjugation almost constantly ; and if it is at all possible to manage it, the students should see the process under the microscope. Conjugating spirogyra can be found late in the summer and in the fall, by collecting very early in the morning. Strings of ladders and zygotes can be preserved in formalin (2 per cent to 3 per cent) or mounted in glycerin for microscopic demonstrations. 72 MANUAL FOR TEACHERS Most of the colleges and experiment stations keep cultures of molds that will enable you to obtain zygote formation in the laboratory. Gametes of rockweed and other algae are best studied from charts, except at the seacoast, where fresh material is available early in the spring. References. For the teacher: COULTER, Evolution of Sex in Plants; COULTER, BARNES, and COWLES, Textbook of Botany, pp. 816-824, 878- 904; GALLOWAY, Biology of Sex; GEDDES and THOMSON, Sex; MORGAN, Heredity and Sex, chap. i. LVII. FLOWERS Where it is possible to have tulips for the first flower, they will be found very useful. Two students can easily work on one flower without mutilating it, and only a few need to be dissected for a whole class. They will keep so that successive classes may use the same material. In many cases it would be no more expensive to have tulips than some other flowers. Whatever flower is taken first should be regular, symmetrical, and perfect. Later other forms may be profitably studied. Flower models are helpful in class dis- cussions, demonstrations, and recitations, as well as for compari- sons of types that blossom at different seasons of the year. There should also be available an abundance of charts. For pollen-tube demonstration, put pollen of various flowers in drops of dilute sugar solution on microscope slides ; keep in moist chamber overnight ; examine with microscope under cover glass. Slices of larger ovaries may be mounted on glass slides and examined with magnifying glasses ; if they are to be kept for some time, place in glycerin. Fertilization in flowers can best be explained with the help of a blackboard diagram that is built up and changed with the progress of the description. References. ANDREWS, Practical Course, pp. 196-223 ; BERGEN and CALDWELL, Practical Botany, pp. 20-23 ; BERGEN and DAVIS, Principles of Botany, chap, xiii, pp. 138-145; COULTER, Plant Life and Plant Uses, pp. 258-301 ; OSTERHOUT, Experiments, chap. vi. For the teacher: COULTER, BARNES, and COWLES, Textbook, pp. 825-834. MANUAL FOR TEACHERS 73 LVIII. POLLENATION - LIX. ADAPTATIONS OF FLOWERS Flowers may be brought to the laboratory for examination as to the mechanism of pollen discharge. Get flowers of grasses, willows, oaks, poplars, maples, etc., as well as those with conspicu- ous corollas. The structure of the bumblebees, honeybees, and other pollenating insects should be studied in this connection. Field trips for the study of insect visits to flowers are most interesting and valuable. Have the students find the pollen car- riers for some of the common wild and cultivated plants. What insects visit more than one kind of flower? What flowers are visited by more than one kind of insect ? Are the visits of mutual advantage in all cases ? Have students find out what evidence there is that the wind brings pollen over a considerable distance. In regions cultivat- ing pedigreed grains and corn, farmers often have to construct windbreaks to prevent foreign pollen from crossing with their special varieties. Hybrid willows and other species of wind-pollenated trees are evidence of such crossing. Study two or three species of zygomorphic flowers that are dependent upon insects, and one or two that are self-pollenating. Visit gardens and greenhouses. Assign special readings and reports on extrafloral nectaries, on specific insect-flower relations, on economic aspects of the relation, and on cleistogamous flowers. References. ANDREWS, Practical Course, pp. 235-249; BERGEN and DAVIS, Principles, chap, xxxii; COULTER, Plant Life, pp. 301-324; DARWIN, Forms of Flowers. For the teacher: COULTER, BARNES, and COWLES, Text- book, pp. 834-878 ; MORGAN, Evolution and Adaptation, chap. i. LX. FRUIT AND SEED DISTRIBUTION Dried fruits of many different species are easily kept in boxes and may be used over and over again, although the collection should be constantly supplemented and enlarged by new additions. Present materials in ecological relations ; that is, in accordance with the agency of distribution or the type of seed protection. 74 MANUAL FOR TEACHERS Field studies along roadsides, vacant lots, and the woods will fur- nish abundant illustrative material and opportunity for collecting. References. ANDREWS, Practical Course, chap, viii ; BERGEN and DAVIS, Principles, chaps, xvi, xxxiii ; COULTER, Plant Life, chap, viii ; OSTERHOUT, Experiments, chap, vii ; Farmers' Bulletins. For the teacher : COULTER, BARNES, and COWLES, pp. 904-929. LXI. ALTERNATION OF GENERATIONS Use fresh or dried moss plants (the pigeon-wheat moss, Poly- trichum, is good and found almost everywhere) showing both gametophytes and sporophytes. Students should see archegonia and antheridia through the microscope, but good blackboard draw- ings or charts are necessary for satisfactory study. Fern prothalli can be grown by sprinkling the spores on moist earth placed in dishes, covered with glass and kept at room tem- perature. Show archegonia and antheridia through microscope. Hydromedusae are best studied in small vials with the magnify- ing glasses. Thus preserved, the specimens will keep indefinitely. References. BERGEN and DAVIS, Principles, chaps, xxiv-xxix ; COULTER, Plant Life, pp. 401-403. For the teacher: COULTER, Evolution of Sex in Plants ; COULTER, BARNES, and COWLES, pp. 92, 264-268, 805-824. LXII. REPRODUCTION IN ANIMALS This subject does not lend itself readily to laboratory or field study by young people ; nor is it always feasible to discuss it in class, especially in mixed schools. Where it is not feasible to keep live fish (see p. 69), it may be possible to arrange for visits to an aquarium or to a fish station, where the students may see roe and milt, and where they may see a demonstration of " stripping " and artificial fertilization. There is a great deal of interesting reading on the breeding habits of common animals, to which students should be referred, even if there is no class discussion of results. References. Special reports on habits of birds, fishes, and other animal groups. MANUAL FOR TEACHERS 75 LXIII. INFANCY AND PARENTAL CARE This is a review study of the whole subject of reproduction, with emphasis upon the relation between parent and offspring, and of the two to the species. This may be correlated with historical and ethnological studies, as well as with social science and community civics. Have students prepare diagrams showing the increasing dependence of spores, gametes, and zygotes upon the parent, in series of plants or of animals. Charts giving a general view of the plant and animal systems are helpful in this connection, even if no attempt has as yet been made to study classification. See Chapters LXXXVI and LXXXVII of the text. Guard against the interpretation of phenomena in terms of " purpose." References. MITCHELL, The Childhood of Animals, especially chaps, i, Hi, iv; PYCRAFT, The Infancy of Animals; BURBANK, Training of the Human Plant ; FISKE, The Prolongation of Youth. PART IV. ORGANISMS IN THEIR EXTERNAL RELATIONS LXIV. OBSTACLES TO LIFE Earlier experiments have already demonstrated the influence of external forces upon growth and upon development. This chapter is in the nature of a summary with a view to a new departure. Have students make (in the form of a table) a list of ten familiar plants and ten familiar animals, with a note on the char- acteristic appearance or behavior (a) at high temperatures (sum- mer) and (b) at low temperatures (winter). Have students state experiences with frostbite, frozen ear, etc., ,with frozen snakes or fish, and so on. Why is freezing of proto- plasm reversible, whereas the effect of heat is irreversible ? What are the dangers of natural ice? What is the object of cooling milk immediately after taking it from the cow ? What is the object of keeping milk and other food at low temperatures? What is the use of pasteurizing milk, and how is it accomplished? What is the objection to boiling milk ? In discussing the effect of water shortage or excess, point out that some of the characteristic summer and winter conditions of plants and animals are due to the water relation. What practical use is made of the fact that protoplasm cannot be active without water ? What practical methods are employed for excluding water from materials that might otherwise be destroyed by bacteria, molds, or yeast ? If the influence of light upon growth has not been demonstrated earlier, it should now be shown with bacteria cultures in petri dishes. Cover a portion of each dish with black paper ; or cover the whole dish and cut distinctive holes or letters in the paper, to admit light. After exposing the sterilized medium to infection, the covers are put on and the dishes are exposed to strong sunlight 76 MANUAL FOR TEACHERS 77 at room temperature or warmer; later they are examined for bacterial growth, showing different behavior in light and darkness. What practical use can be made of the fact that light is injurious to protoplasm (as in bacteria) ? Refer to the use of ultraviolet rays for the sterilization of water supplies and other food materials. Have students make special reports. What practical use is made of the fact that many salts (chemi- cals) are injurious to living things ? Refer to the use of salt or ashes on the ground for killing weeds. In the use of salt (and sugar) for preserving food, part of the effect is no doubt due to the drying. Compare the drought characteristics of many swamp plants, such as the mangrove. References. For the pupils : COULTER, BARNES, and COWLES, Textbook of Botany, pp. 565-589, 704-718; DARWIN, Origin of Species, chap, iii; JORDAN and KELLOGG, Evolution and Animal Life, chap. iii. For the teacher: MORGAN, Experimental Zoology, chap. ii. LXV. THE CONFLICT OF LIFE WITH LIFE Most of the ideas in this chapter deal with abstractions that cannot be illustrated or demonstrated directly, as predation, parasitism, competition, or struggle. But these ideas can be easily formed from familiar examples. Have specimens of tapeworm and microscopic preparations and pictures of roundworm, hookworm, and other parasites. Students can suggest many examples of predatory and parasitic re- lations, and comprehensive lists can be compiled from their reports. Selective and nonselective elimination should offer no difficulty ; examples abound on every side, in human affairs as well as in those of the common animals and plants. The important thing is to make clear the metaphorical sense in which the word struggle is used, and to form connotations that avoid the banal element of competition. References. BERGEN and CALDWELL, Practical Botany, chap, xxi ; BERGEN and DAVIS, Principles, chap, xxx ; DARWIN, Origin, chap, iv ; EALAND, Insects and Man, chap, vii; HODGE and DAWSON, Civic Biology, chaps, xviii, xx, xxiv; JORDAN and KELLOGG, Evolution and Animal Life, chaps, v, xvii. For the teacher: MORGAN, Evolution and Adaptation, chaps, iv, v ; MORGAN, Experimental Zoology, chap. xiii. 78 MANUAL FOR TEACHERS LXVI. PROTECTIVE ARMORS OF ORGANISMS It is not worth while to study skin structures of plants and animals in detail. Illustrative specimens should be on hand, and visits to museums, gardens, menageries, aquaria, etc. encouraged. The general ideas discussed are simple enough and should not take too much time beyond the reading and summarizing in note- books, with perhaps additional examples. References. BERGEN and DAVIS, Principles, chap, xxxi; COULTER, BARNES, and COWLES, Textbook, pp. 741-744. LXVII. PROTECTIVE PIGMENTS AND APPEARANCES That colors, patterns, etc. may protect is obvious enough. More difficult, and perhaps more important, is the idea that the resem- blances etc. may be quite fortuitous and without practical signifi- cance either in the lives of the organisms or in the evolution of species. Have prepared specimens to illustrate protective colora- tion, warning coloration, and mimicry ; have museum studies and encourage students to bring in specimens found afield. What experiences have the students had with sunburn and tan ? Refer to Cunningham's experiment with flatfish. What experiences have the students had with the behavior of animals that show dependence upon the coloration etc. ? Have cactus and other xerophytic plants to illustrate reduction of surface as an adaptation. Get some students to experiment on whether the drought brings about the reduction of surface, as a modification during development, or whether these plants are incapable of living where there is a relative excess of water. References. For the pupils : DAVENPORT, Elements of Zoology, pp. 35-38 ; JORDAN and KELLOGG, Evolution and Animal Life, chap, xix ; KELLOGG, American Insects, chap, xvii; POULTON, The Colors of Animals; WAL- LACE, Natural Selection and Tropical Nature, chap. v. For the teacher: MORGAN, Evolution and Adaptation, pp. 357-360. MANUAL FOR TEACHERS 79 LXVIII. PROTECTIVE MOVEMENTS LXIX. PROTECTIVE ACTIVITIES Have students handle live animals of various kinds, in the aquarium and in the vivarium at school or wherever they can outside, and report the contracting and flight movements. Many of these movements are already familiar enough, and too much time should not be taken for their consideration in the classroom. " Playing possum " is a widespread reaction ; point out that it is a general reaction that may or may not be useful, and that may or may not be related to the advantage of the species. Have specimens of fence lizards and other chameleons, and note color changes in other reptiles, in batrachians, and in fishes. Where there is opportunity the students that take an interest in morphology may be encouraged to study homologies and analogies in animal appendages. Individual students might pre- pare mounted series of crustacean or insect appendages and mouth-parts. Special reports on bird and fish migrations should include results of field observations as well as of reading. Laboratory and field studies of burrowing worms and insect larvae, and of birds' nests. Charts and microscopic demonstration of nettling cells. Study of leaf-scars to show self-healing surface; microscopic preparation of the scission layer. Encourage students to collect insect galls and to find out what insects cause them on common plants. Have special reports made on field observations and readings on the homing habits of animals, from the point of view of protection. References. COULTER, J. G., Plant Life and Plant Uses, pp. 242-247; COULTER, BARNES, and COWLES, Textbook, pp. 354, 582-588 ; OSTER- HOUT, Experiments, pp. 212-215, 332. For the teacher: MORGAN, Experi- mental Zoology, chap. xvi. 8o MANUAL FOR TEACHERS LXX. THE FOREST IN RELATION TO MAN The forest has for a long time been the favorite hook upon which to hang the sermon of conservation, since it lends itself admirably to the purpose, both for economic reasons and for biological ones. FIG. 12 The slope consists of a wooden frame, supported at an angle of about 45 degrees, inclosing a pane of glass with a trough at the bottom leading to a small drain-hole at the end. The most convenient size is that of the large blotters used on desks or in desk pads. Two beakers, two cylinders, preferably graduated, a florist's spray, and a supply of water complete the equipment. Equal quantities of water are placed in the cylinders or graduates. The water from one of these is drawn into the bulb of the spray and rained first upon the bare glass, representing a deforested mountain side, and then upon the slope covered with two blotters, one representing the forest trees and the other representing the forest floor, or duff. In each case as much water as possible is collected in the beaker and returned to the respective cylinders for comparison. The water can be seen across the schoolroom more easily if it is slightly colored, as with a few drops of red ink. (Apparatus designed for use in the Department of Public Education of the American Museum of Natural History by George H. Sherwood, Curator) This subject is perhaps best studied in connection with Arbor Day observance. Special reports on various aspects of the forest in relation to human welfare furnish the best means of arousing interest and impressing the students with the far-reaching contacts MANUAL FOR TEACHERS 8 1 between the forest and human affairs. These reports may take the form of statistical reports on such topics as the quantities or values of various forest products ; water supply, navigation, water power ; soil erosion ; harbor maintenance ; Value of improved lum- bering methods; injurious species of insects and fungi, and specific methods of control ; the birds in relation to the forest ; danger of fire and the prevention of fire ; relative values of different kinds of wood ; different rates of growth ; methods of reforesting ; special services of state and federal bureaus ; recent legislation ; etc. The effect of clearing upon soil erosion, floods, etc. is often demonstrated by means of the model illustrated in Fig. 12. This demonstration does not, of course, prove that the forest retains water longer than does the nude soil ; it only helps to visualize the relationships between the two kinds of hillside and the run-off. References. BERGEN and ' CALDWELL, Practical Botany, chap, xxii ; COULTER, J. G., Plant Life, pp. 195-200; HODGE and DAWSON, Civic Biology, chap, vi ; MOON, The Book of Forestry ; ROGERS, The Tree Book. Yearbooks of the United States Department of Agriculture ; re- ports and bulletins of the United States bureau of Forestry; bulletins and reports of state departments of agriculture ; United States Depart- ment of State, publications on forest reserves and recreation. LXXI. BACTERIA AND HEALTH - LXXII. CONTROL AND USE OF BACTERIA The subject matter here is largely in the nature of a new synthesis of material that is for the most part already familiar. The destruction of bacteria discharged from diseased persons, and the prevention of infections, are the practical problems sug- gested. Various methods, materials, and regulations directed to these ends should be correlated with the data given in the table on page 387. Have specimens of the germicides to be used in various situations ; and perhaps make comparative studies of their effectiveness with petri-dish cultures. An interesting experiment in connection with this study is to obtain cultures from a mouth- rinsing thrown into a petri dish, and then a similar rinsing after the use of a commercial mouth wash. 82 MANUAL FOR TEACHERS Special reports on methods and regulations in hospitals and sickrooms are interesting and valuable. Typhoid carriers are presented to the public attention from time to time ; local and current references are more interesting than remote cases. Special studies may be made of local conditions and current activities in the way of legislation and administrative regulation, with reference to the various items mentioned in the latter part of Chapter LXXI and in section 434 of Chapter LXXII, and with reference to markets, cold-storage plants, etc. Analyze city or state health department reports of morbidity and mortality. For the economic aspects, reports upon accessible industries men- tioned in the text, or other local activities in which microorganisms play a part, and the collection of commercial products or specimens illus- trating processes, should be encouraged. Have demonstrations of such specimens in class, and, in some cases, of actual processes, as the souring of vinegar and the rotting of flax or of sponges. References. BUCHANAN, Household Bacteriology ; CONN, Agricultural Bacteriology ; HODGE and DAWSON, Civic Biology, chaps, xxi-xxiii ; HOLMES, Animal Biology, chap, xxxvi ; JORDAN, Textbook of General Bacteriology, chap, xxxiv ; LIPMAN, Bacteria in Relation to Country Life, chaps, i, xxxvi-xlix ; LOCY, Biology and its Makers, chap. xiii. Bulletins and reports of the local and state departments of health and of the United States Public Health Service. For the teacher: CHAPIN, Sources and Modes of Infection ; JORDAN, Textbook of General Bacteriology, chaps, i, v, xxii, xxxiv. LXXIII. INSECTS AS SPREADERS OF DISEASE Prepare a number of petri dishes with nutrient agar or gelatin. Have students bring in flies caught in various parts of town and in various situations. Place a fly in each dish, after clipping off the wings, and keep in a warm place for two or three days. Do not omit several control dishes. Have students summarize results in tabular form. Have surveys made of various parts of town accessible to the students, to find out the relative prevalence of flies (especially in MANUAL FOR TEACHERS 83 relation to food markets) and the distribution of breeding places. Where the flies have not been virtually exterminated through the efforts of the community, it is legitimate to undertake a systematic campaign, in cooperation with official bodies and civic organiza- tions. Where the fly is no longer a pest, this study has only a historical interest ; but the history is so recent that it is worth impressing as an example of man's control of his environment. References. CHAPIN, Sources and Modes of Infection, pp. 417-447; EALAND, Insects and Man, pp. 119-136; HODGE and DAWSON, Civic Biology, chap, x ; KELLOGG and DOANE, Economic Zoology, pp. 377-384 ; KELLOGG and DOANE, Insects and Disease; RILEY and JOHANNSEN, Handbook of Medical Entomology, chap. v. Bulletins and reports of local and state departments of health; bulletins of the United States Public Health Service and of the United States Department of Agriculture. LXXIV. INSECTS AS INTERMEDIATE HOSTS Get first a quantitative idea of the prevalence of malaria (or yellow fever ! ) in the locality. Students should set out to find possible breeding places for mosquitoes, and chart their distribu- tion. Study local operations directed toward the extermination of mosquitoes. Have special reports on the sanitary work in the Canal Zone and in Cuba. Have special reports on sanitary work in the nearest harbors. Draw diagrams illustrating the idea of alternate hosts. Have special reports on the extermination of parasites through attacks upon intermediate hosts. References. CHAPIN, Sources and Modes of Infection, pp. 380-417; EALAND, Insects and Man, pp. 88-119, 136-159, chap, iv; HODGE and DAWSON, Civic Biology, chap, xi ; JORDAN, Textbook of General Biology, chap, xxx ; KELLOGG and DOANE, Economic Zoology, pp. 367-377. LXXV. INSECTS AND HUMAN WEALTH Collect specimens of useful and destructive insects, including the various stages wherever possible ; specimens of commercial products and of stages in industrial processes ; specimens of spoiled materials ; insecticides. 84 MANUAL FOR TEACHERS Have special reports on life histories, injuries, and means of fighting destructive insects, and on life histories, value, and means of cultivating useful insects. Study the statistical data. Give special attention to economic insects of local or current interest. References. EALAND, Insects and Man, chap, v; HODGE and DAWSON, Civic Biology, chap, xii; KELLOGG, Insect Stories; KELLOGG and DOANE, Economic Zoology, chap. xvii. Bulletins and reports of state and United States departments of agriculture ; farmers' bulletins and yearbooks, United States Department of Biology. LXXVI. INSECTS AND OTHER ORGANISMS Collect specimens of insects injurious to useful plants (complete life histories if possible), together with specimens of the plants in question. Species of local or current interest should receive special attention. Have special reports on life histories, extent of damage, and means of control. Make a similar study of insects related to economic animals. Wherever possible, students should be encouraged to mount specimens of economic insects in arrangements showing their relations, for example, a twig with scales and lady-beetle, or life history of gypsy moth, life history of calosoma, and twig of host plant. Have special reports on state and federal activities in the culti- vation of insects for the destruction of injurious insects. Have reports on spraying and other methods of control ; study a spraying calendar etc. New examples of the interrelations of species should be re- corded ; study the fate of introduced species of plants and animals, and the effects of introduced species upon native species. References. EALAND, Insects and Man, chaps, ii, viii ; HODGE and DAWSON, Civic Biology, chap, xiv; KELLOGG and DOANE, Economic Zoology, chaps, xxx-xxxvii. Bulletins of the United States Bureau of Entomology ; state bulletins. MANUAL FOR TEACHERS 85 LXXVII. BIRDS IN RELATION TO MAN Have field observations on resident and migrating birds. En- courage students to become acquainted with the identities and habits of birds, including distinctive songs, notes and calls, and food plants and animals. The " shooting " of birds with cameras, and their " capture" by means of suitable nesting boxes etc., offer worthy substitutes for the expression of primitive gaming instincts, and should be encouraged. Have special reports on life habits and economics of important birds, particularly such as are of local or current interest. Summaries of the various reports should be prepared in tabular form, and should include information about habitats, seasons, and food plants and animals. References. BAYNES, Wild Bird Guests ; BEEBE, The Bird ; HODGE and DAWSON, Civic Biology, chaps, iv, v; HOLMES, Animal Biology, chap, xxi; JOB, Domestication of Wild Birds. Reports and farmers' bulletins, United States Department of Agriculture ; annual summaries of game laws, United States Department of Agriculture; publications of the State Department of Agriculture ; publications of the Audubon Society. LXXVIII. SOCIAL LIFE OF ORGANISMS Have specimens illustrating high points in the evolutionary series, both plant and animal ; or provide suitable charts. The emphasis will be upon the differentiation that follows upon inte- gration, and this should be compared with the parallel process observed in the course of development (Chapter LI 1 1). Access to a glass beehive or to an ants' nest under glass is desirable. Have special reports on division of labor in ant and bee colonies. The distinction between the automatic coordinations that obtain in such colonies and the conscious cooperation of various human enterprises should be made clear. References. FABRE, Social Life in the Insect World; HODGE and DAWSON, Civic Biology, chap, xiii ; HOLMES, Animal Biology, chap, vii; JORDAN and KELLOGG, Evolution and Animal Life, chap, xviii ; KELLOGG, American Insects, pp. 490-561 ; KROPOTKIN, Mutual Aid; LUBBOCK, Ants, Wasps, and Bees; MAETERLINCK, The Bee; WHEELER, Ants, especially chap, xxiii. PART V. HEREDITY AND EVOLUTION LXXIX. VARIATION For the study of variation, use any organic structures available in quantities. Leaves are to be obtained in all regions and are easily preserved for use in all seasons. Fingers of girls and boys, feathers of birds, claws or teeth of mammals, wings of insects, shells of mollusks, pulse beats, ray-flowers, and hundreds of other things are just as good. Have a group of specimens matched as to form, for example, maple leaves or finger prints. Make a census of careful measurements. Distribute the material in small boxes, envelopes, or bottles, with rulers or scales divided to millimeters. Instruct students to sort the material into classes representing differences of one or two millimeters. A class of ordinary size can obtain several hundred measurements in a short time ; have a committee of students compile the results. If several classes are doing parallel work, it is worth while to consolidate the data for all and illustrate the increased smoothness of the curve obtained from large numbers. Have results presented graphically as well as in tables. Have them posted on blackboard or chart, and if possible have a copy made for each student. When the idea of variation is fairly clear, have students bring in examples of variations, physiological as well as meristic etc., that they have themselves observed among human beings and among other organisms. Have them suggest for each variation what the possible advantage or disadvantage of extremes may be to the organism. It is worth while, in connection with this study, to have pupils record their opinions or beliefs as to the causes of the variations observed ; these views are to furnish a basis for further analysis, or hypotheses for further study, leading to a clearing up of the thought. Examples of modifications in which the causes are 86 MANUAL FOR TEACHERS 8/ obvious or inferred with some degree of probability should also be collected. Have noted the modifying effects of disease, exercise, or disuse, nutritional extremes, habit formation, mechanical injuries, injuries caused by insects or other animals, etc. Have pictures and charts showing various breeds of domesticated animals and plants and different varieties of cultivated fruits, vege- tables, and flowers ; study seed catalogues, poultry catalogues, etc. Have special reports on new varieties of useful or fancy plants and animals, from the United States Department of Agriculture year- books, from reports of the nearest agricultural experiment station, from the State Department of Agriculture, from the reports of breed- ers' associations, etc. Have a special report on the work of Burbank. References. BERGEN and CALDWELL, Practical Botany, pp. 417-421, 428-430; JORDAN and KELLOGG, Evolution and Animal Life, chaps, ii, ix. For the teacher : BATESON, Materials for the Study of Evolution ; DAVEN- PORT, Principles of Breeding, chaps, i-v ; MORGAN, Evolution and Adap- tation, pp. 261-270; VERNON, Variation. LXXX. HEREDITY In having students bring in examples of family resemblances, consider mental .traits that are not likely to be the results of habituation or common experience, as well as physical traits. Simi- larities in voice, pronounced likes or dislikes, the manner of folding the hands, various mannerisms, and physiological idiosyncrasies furnish interesting material for study and comparison. Uncles and cousins and aunts should be considered, as well as parents and grandparents. The most valuable outcome of such studies should be a clear realization of the fact that the resemblance to the two houses is a resultant of many complete resemblances to one side and many complete resemblances to the other, rather than a blending of the several characters. Have a special report on the alternative characters studied by Mendel. Have specimens and pictures of varieties of cultivated plants and animals, for study of alternative characters, students to find as many pairs as possible in a given set of individuals. 88 MANUA^ -FOR TEACHERS Use blackboard and colored crayons for developing the Men- delian principles. Use checkerboard diagram to show the segre- gation of two or more characters. Where possible, show identity of the segregation formula with the algebraic formula for the square of a binomial etc. To make clear what is meant by chance in scientific discussions, refer to (or demonstrate in class, or assign for trial and report) the experience of drawing cards from a pack or of throwing a coin or dice. The chances are even that a card drawn at random will be black or red ; that a coin will fall heads up or tails up. A second throw of a coin faces the same chances, and so the third and the millionth. But the chances that all in the series will fall the same way are very small; and the longer the series, the smaller the chances. It is possible for a coin to come heads up six times in succession; but it is more likely to come in some other succession, as there are a great many possible others. Yet, if we took any one of the others, the chances that that one would come up are just the same as the chances that the six heads would come up. Now the larger the number of throws, the greater the possible number of combinations, and the smaller the chances of any particular combination falling out. With three throws there are eight possible combinations (2 3 ), any one of which has one chance in eight of appearing ; with four throws there are sixteen possible successions (2 4 ), and each has one chance in sixteen of appearing ; with five throws there are thirty-two combinations ; and so on, the chances for a special combination diminishing in geometrical ratio. When this idea is applied to the combination of alternative characters derived from the two ancestral lines, we can see that the chances of a particular combination of characters being duplicated are practically one in infinity. References. For the pupils : CASTLE, Heredity in Relation to Evolution and Animal Breeding ; DONCASTER, Heredity in the Light of Recent Re- search ; GUYER, Being Well Born, chaps, i, iii, iv ; HOLMES, Animal Biology, chap, xl; JORDAN and KELLOGG, Evolution and Animal Life, chap. x. For the teacher : LOCK, Variation, Heredity, and Evolution, chaps, vii, Viii; MORGAN, Heredity and Sex; PEARSON, The Chances of Death; THOMSON, Heredity. MANUAL FOR TEACHERS 89 LXXXI. APPLICATIONS OF THE PRINCIPLES OF HEREDITY Have special reports on the economic and esthetic contributions of plant and animal breeding, from recent bulletins and current publications. Have specimens (where possible) and pictures of new combinations brought about through the systematic applica- tion of known facts and principles. Assign readings on eugenics. References. BAILEY, Plant Breeding; BERGEN and CALDWELL, Practi- cal Botany, chap, xxiii ; CASTLE, Heredity in Relation to Evolution and Animal Breeding; DAVENPORT, Principles of Breeding, chaps, xix, xx; GUYER, Being Well Born, chaps, v, vii, x ; HARWOOD, New Creations in Plant Life. Yearbooks and bulletins of the United States Department of Agriculture; seedsmen's catalogues. For the teacher: CASTLE, COULTER, and others, Heredity and Eugenics ; DAVENPORT, Heredity in Relation to Eugenics ; GODDARD, The Kallikak Family. LXXXII. HEREDITY AND PROTOPLASM It should be clear that whatever is inherited is not physically passed on, the red cow is just as red after the calf is bom as she was before ; and the fertilized egg of the leghorn has not white feathers, it has no feathers at all, not even in miniature. Get the idea of the immortality of the germ plasm by comparing with the immortality of protozoan protoplasm. Show stained cells for karyokinesis. Show stained egg cells, as of Ascaris, for chromosomes and reduction. Explain the suc- cessive steps in reduction and maturation divisions with the help of blackboard diagrams. Have students make special reports on sports among animals and plants. Discussion of the transmission of modifications will probably arise without special stimulation from the teacher, it always does if there is the slightest occasion. The question of prenatal influ- ence and of the cause of birthmarks should also be given a chance if it presents itself. References. CONKLIN, Heredity and Environment in the Development of Man, chap, ii ; GUYER, Being Well Born, chap, ii ; LOCK, Variation, Heredity, and Evolution, chap. x. QO MANUAL FOR TEACHERS LXXXIII. EVOLUTION Review the idea of universality of change, and emphasize the practical importance of understanding changes. Have students give examples of the use of knowledge to bring about desirable change, to avoid undesirable change, etc. Have examples of continuously progressive changes and of cyclic changes. Does history repeat itself ? Guard against the tendency to assume that we must pin our faith to a yes or a no answer to every question. There are perhaps other possibilities, and both types of change may exist side by side. Show fossils peculiar to the region, and geographical varieties of plants and animals. Have museum studies of fossil series and of morphological series. Explain what a reconstruction is, its basis, and the degree of its validity. Present alternative theories or hypotheses to account for fossils. Have special readings (with reports) on the various classes of evidence for descent with modification. It is important to avoid the tendency to confuse the evidence for evolution, considered as a purely historical fact, with speculations concerning the mechanism of evolution. References. HOLMES, Animal Biology, chap, xxviii ; JORDAN and KELLOGG, Evolution and Animal Life, chaps, iv-ix. For the teacher 1 : LOCK, Variation, Heredity, and Evolution, chaps, i-iii, v ; MORGAN, Critique of the Theory of Evolution, chap, i ; MORGAN, Evolution and Adaptation, chaps, ii, iii. LXXXIV. APPLICATIONS AND THEORIES OF EVOLUTION The time given by high-school or college students to the study of evolution must justify itself not in a resulting familiarity with theories or with illustrations and statistics ; it must justify itself in a resulting attitude toward life. It may well be that a portion of our population is constitutionally incapable of acquiring a dynamic outlook ; but where there are no constitutional barriers, the failure to acquire this dynamic viewpoint must be charged to the school and specifically to the teachers of biology and history. MANUAL FOR TEACHERS 91 The study of this section may well take the form of a free dis- cussion that will ferret out lingering doubts and prejudices, not for the purpose of inculcating sound doctrine on the subject of evolution, but for the purpose of getting the students to feel the majesty of the larger concepts. An academic analysis or a purely intellectual assent is not sufficient. Have special reports and summaries on the views of Lamarck, Darwin, De Vries. Have reports on experimental work in evolution. References. CONKLIN, Heredity and Environment, chap, v; GUYER, Being Well Born, chap, x; HARWOOD, New Creations in Plant Life. Yearbooks of the United States Department of Agriculture. For the teacher: KELLOGG, Darwinism To-day; LOCK, Variation, Heredity, and Evolution, chap, x; MORGAN, Evolution and Adaptation, chap. iv. PART VI. MAN AND OTHER ORGANISMS LXXXV. THE CLASSIFICATION OF ORGANISMS - LXXXVI. KINDS OF PLANTS LXXXVII. KINDS OF ANIMALS It is not to be expected that students will attain to a clear view of the plant and animal series from the study of a chapter or a chart. It is only through prolonged association with many forms, and through constant thought upon similarities and differences and relationships, that this is to be attained. As a means of facilitating acquaintance with forms, present constantly new specimens to illustrate the biological principles studied. These new specimens come to the student as laboratory material for direct handling ; as demonstration specimens ; as exhi- bition material in the wall cases etc. of the classroom ; as objects of observation in the field, in museums, in the flower or vegetable show, in the bird store, in the menagerie or at the circus, in pictures found in books and magazines and upon the classroom walls etc., in stereopticon and motion-picture views, and so on. Acquaintance with forms is the beginning ; classification and naming come later. But children begin to classify and name almost as soon as they begin to speak. Call attention to the way children name a new object in terms of the familiar one which it most resembles. Discuss the difficulty of supplying enough common names, the inadequacy of common names, and the binomial system as applied to proper names. The basis of classification offers opportunity for making students realize both the practical importance of adequate classification and the practical difficulties of establishing a satisfac- tory classification. For the purpose of getting hold of principles of classification, experience with postage stamps, books, pottery, and textiles may be quite as illuminating as experience with flowers or fishes or frogs. The only advantage of experience with the sorting of organisms lies in the suggestion of a natural order. 92 MANUAL FOR TEACHERS 93 Where opportunity and interest are present, encourage students to attempt the identification of species with the aid of some manual. As a means of facilitating thought about relationships, tables and " trees " similar to those in the text should be constantly be- fore the eyes of the students. It is therefore desirable to have large charts or wall paintings of these fixed points wherever feasible. It is especially recommended that a large portion of the bare wall, above the blackboards, be devoted to outline "trees" with the names of the phyla and chief subdivisions, accompanied by outline sketches of illustrative forms from the more familiar species. As reference is made to one or another species of plant or animal during the course of the year's study, the teacher may lightly indicate the place of the species in the system as a whole, orient without elaborating. More can be achieved by this constant repetition through a long period than by devoting the same amount of time to intensive study of charts and tables and manuals. En- courage students to transcribe portions of the tables for special groups, and to prepare larger diagrams for the classroom wall. Apart from the general features of the classification schemes, the significant point of the discussion is the basis for distinguishing between higher and lower plants and animals. This is to be considered with constant regard for .the fact that the lowest are quite as capable of living as the highest, while it is legitimate to bring out the important differentia of human life as the highest. References. Manuals for the classification and identification of common flowering plants (including trees), ferns, mosses, common fungi, birds, insects, fishes, reptiles, batrachians, and mammals. Natural-history books. LXXXVIII. MAN AND HIS RELATIVES This study may serve as a summary of the common facts about animal organization and functions. Use pictures, plaster casts, relics of primitive man ; have museum studies. Have special reports on traces of aborigines in the neigh- borhood and on current topics related to man's ancestry. The argument is essentially a successive differentiation of man from the invertebrates to the primates. 94 MANUAL FOR TEACHERS The common argument that the similarity between man and the lower primates appeals even to the least intelligent must not be pushed too far. The resemblance that appeals may be en- tirely superficial. Young children are quite satisfied to treat dogs and cats exactly as they treat human beings ; that is, there is enough similarity to appeal to their intelligence. Savages attribute to other animals and even to inanimate forces their own type of purpose and thought. This obvious similarity may thus prove too much. It is necessary to consider similarities that indicate rela- tionship in the biological sense. That is, we must separate what men and monkeys have in common with other animals from what they have together that is different from other animals ; and then we must consider the points of difference between man and other pri- mates, with a view to determining whether these differences are so radical in kind or degree as to preclude evolutionary relationship. References. CLODD, The Childhood of the World, chaps, i-iv ; DARWIN, Descent of Man, chaps, i, vi, vii ; DUCKWORTH, Morphology and Anthro- pology, chaps, ii, vii, viii; HOLMES, Animal Biology, chap, xxii ; HOLMES, Evolution of Animal Intelligence, chaps, xi-xiii ; HUXLEY, Man's Place in Nature ; JORDAN and KELLOGG, Evolution and Animal Life, chap, xxi ; OSBORN, Man in the Old Stone Age; SPURRELL, Modern Man and his Forerunners, chaps, ii, iii ; TYLOR, Anthropology, chaps, i-iii ; WATSON, Behavior, chap. x. LXXXIX. MAN'S BRAIN Since the significant part of this study has to do with the results of brain work rather than with the structure and workings of the brain, the latter need not be emphasized unless there is special interest in the subject among the students. Use a model of the human brain, and of such other vertebrate brains as are to be had. A calf's brain from the butcher may be dissected for gross features. Have special readings and reports on museum studies on the activities of primitive man, comparing them particularly with the corresponding activities of other animals. The question to emphasize is, How does man, despite his struct- ural shortcomings, manage to adjust himself to the inimical aspects of his environment, and how does he manage to supply his needs ? MANUAL FOR TEACHERS 95 References. For the pupils : DARWIN, Descent of Man, chaps, iii-v ; TYLOR, Anthropology, chaps, iv-xii. For the teacher : DONALDSON, The Growth of the Brain ; LANKESTER, Nature's Insurgent Son ; LOEB, Com- parative Physiology of the Brain. XC. MAN'S CONQUEST OF NATURE - XCI. SCIENCE AND CIVILIZATION Man the organic mechanism is gradually replaced by man the designer and creator. The isolated animal supplying his own wants and meeting his personal difficulties is gradually replaced by a member of society. Now he hunts in groups and solves his other problems through interchange of service and experience, and through cooperative effort in many directions. The study of biology merges into the study of psychology and sociology. The study of man is no longer physiology, but anthropology, ethnology, politics, and economics. The text should be supplemented by assigned readings along divergent lines, depending upon the interests of the students and upon the available material. Local relics of ancient times and local institutions that embody the highest achievements in the way of organized research are equally significant in the final synthesis. The visit to the museum of natural history may well be supple- mented by a visit to the historical museum or to the art museum ; for here, in the consideration of man's achievements, the study of nature passes into the study of history and art. The study of recent statistical material indicating measurable progress in man's conquest of his environment, and the comparison of local conditions in various respects with the general conditions, will help to fix the interest and perhaps to widen the outlook. The emphasis should be finally upon the value of civilization in terms of life more abundant, to which all science must contribute. References. CLODD, The Childhood of the World; CONN, Social Heredity and Social Evolution; HODGE and DAWSON, Civic Biology, chaps, xxxi-xxxii ; KELLICOTT, Social Direction of Human Evolution ; LANKESTER, Nature's Insurgent Son; SPURRELL, Modern Man, chaps, iv- vii ; TYLOR, Anthropology, chaps, xiii-xvi. Current reports of progress in applied knowledge. SEP 'OLOGY LIBRARY 1932 31 1935 2 1964 i<2 JIOLOGY LIBRARY ., UNIVERSITY OF CALIFORNIA LIBRARY