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 -/I. I 
 
 THE BIOLOGICAL BASIS OF MKNSTRUATION. 
 
 BY 
 
 J. C. WKB.STKR, M.D., (Kdin.), F.K.C.P.K., F.RS.E. 
 
 (Reprinted from the Montreal Medical Journal, April, 1897.) 
 
I VAV" • 
 
 I ■ H 
 

 •^!P"S^E5 
 
 THE BIOLOGICAL BASIS OF MENSTRUATION.' ^ 
 
 J, C. Webster, M.D., (Edin.), F.R.C.P.E., F.R.S.E. W^ fCcti/^ llvyfu/alP ^^^M 
 
 At the presimt time there is universal ignorance as regards the 
 causation of menstruation, its meaning as a sexual character, and the 
 method by which it has become established among the higher mam- 
 malians. 
 
 The following views have been advanced to explain the meaning of 
 the process : 
 
 1. Relatiov to Ovulatioii. — For a long time it has been believed 
 that ovulation and menstruation are so closely related that they occur 
 at or about the same time, the former being the cause of the latter. 
 
 Of those who hold this view, some think that the blood-discharge 
 results from a general pelvic congestion, supposed to be present during 
 the ripening and escape of the ovum. Thus, Mathews Duncan often 
 compared the menstrual flow to the red flag outside the door of an 
 auction-room, which indicates that something is taking place inside. 
 
 Others regard menstruation as a process induced by ovulation 
 necessary to the preparation and development of the ovum, in case it 
 should be fertilized. 
 
 A careful examination of tlie evidence on which these statements 
 are founded reveals their untrustworthiness. It is, indeed, a wonder 
 that they have so long been believed. 
 
 The following facts relating to maturation and escape of the ovum 
 are now definitely ascertained. These processes are usaally in opera- 
 tion some time prior to the development of the phenomena of puberty 
 before menstruation appears ; sometimes they occur in childhood and 
 
 • Read before the Montreal Medico-Chirurgical Society, Jany. 12th, 1897, and 
 before the New York Academy of Medicine. 
 
2 
 
 in fd'tal life. There is no proof at all that pelvic confrcstion takes 
 place, either coincident with or secondary to these processes, at any 
 time in a woman's life. 
 
 Ovulation may also occur without menstruation in the dodj^inj^- 
 period of puberty and of the menopause ; for several years after the 
 menopause as Hej^ar has pointed out ; durin<f lactation ; in certain 
 diseased conditions, rr/., ananuia, phthisis, iead-noisoninn'. Prej^niancy 
 may take place at any of these times. DeSinety tlescrihes an inter- 
 esting case whicli he examined, of a woman, -SiS years ot age, who had 
 n(!ver menstruated. In the ovaries tlun^ was the normal condition of 
 Graafian follicles, and corporn lufco, indicating that ovulation had 
 taken place. The body of the uterus was undeveloped. 
 
 Then, in abdominal and post-mortem sections made at all times 
 between menstrual periods, (ili-aatian follicles may be found ,jn the 
 point of rupture or recently ruptured ; and in examinations made 
 during menstruation, no sign of ovulation may be visible. 
 
 (In this connection it is intei'esting to note that Heape examined 
 the pelves of forty-two moiikeys (Semnoj>ithecui< enteUns) during 
 their menstrual periods and found evidences of ovulation being in 
 progress in only two cases.) 
 
 It is a common observati<ai that extensive disease of both ovaries, 
 e.g., cystoma, suppuration, malignant growth, may not effect the men- 
 strual function to any appreciable extent in man}' cases. 
 
 These various facts are sufficient, it seems to me, to overthrow the 
 view that menstruation is a necessary accompaniment or setpiel of 
 ovulation. 
 
 Yet it can scarcely be denied that there is some relationship between 
 the proce.sses. 
 
 Removal of the ovaries is followed by ces.sation of menstruation 
 though in a certain number of eases this does not happen. As an 
 interesting instance of this, may be mentioned Law.son Tait's patient 
 from whom both ovaries and tul)es along with a part of the uterus 
 were removed, menstruation still continuing. 
 
 The.se exceptions have been carefully considered by several authori- 
 ties, lately by Bland Sutton. He states that the reported cases have 
 been mostly tho.se in which chronic inflammation in and around the 
 a|(pendages has been present, or those in which operation has been 
 performed for myoma uteri. His explanation of the pi-rsi.stent men- 
 sti'uation is that either small bits of the ovary have been left behind) 
 or that in the cases of myoma a submucous tumour may exist leading 
 to h;emoi'rhages. Many cases have undoubtedly iiecn iceordeil in 
 
8 
 
 whicli after removal of the ovaries for fibroid, menstruation has con- 
 tiniK'd. 
 
 The lonj,' held vi('wV)f supcrnunicrar}' ovaries is discarded hy lilaml 
 Sutton. He thiidvs that these so-calle<l structunss are merely small 
 V)its separated from the main mass of the ovary l)y deep fissures. 
 
 In .several of these cases of unchecked menstruation, second opera- 
 tions have heen performed hy which small hits of ovary left from the 
 first operation have lieeii reirov(!d, lieiny foUoweil l)y a c(»mplete 
 ce.ssation. 
 
 2. Relai'um to llw FnlLopiKii Tithes. — According' to Lawson Tait, 
 removal of the tuhes, the ovaries heinj; left 1 o situ, is followed in 95'^ 
 of cases hy cessation of menstruation. This remarkahle statement 
 has Iteen little noticed. If itcan lj(> estalilished hy extended ohserva- 
 tions, it proves that there is some close relationship lietween the tuhes 
 and the menstrual process. 
 
 3. Rddt'ioii to (I Spcciiil N^ervonn Mcclm/nUm. — Johnstone has 
 aiivanct '1 the www, sup[)orted hy Lawson Tait and others, that the 
 menstrual act is a special function related to a distinct n"rvous 
 mechanism. They think that possiliiy a special nerve trunk running 
 in the upper part of the hroad ligament may convey the regulating 
 currents. Johnstone suojt'ests that irlien ilic ova ricx or lubes are 
 renwvf'd, iivnstriuu'on Is checked hecauae thin nerve is l'u)(itv,red or 
 divided. In the rases in which removal of the appendages is not 
 followed hy ces.sa^ion of the How, he thinks that the nerve may have 
 escaped division cr ligature, owing possibly to its being placed low in 
 the broad ligament. 
 
 While undoubtedly believing in this special nervous mechanism of 
 menstruation it seems to me tliat possibly the nerve tract is not so 
 limited as Johnstone suggests. The plexifonii nature of the nerves 
 about the uterus is .so complex that it is pres\imalile that the impul.ses 
 artecting the muco.sa of the uterine boily travel by many routes in the 
 broad ligaments. 
 
 4. ReiatUni of Menstruation to ConcepfioiK — By .some it is believed 
 that menstruation is a process for preparing tht; utei'ine mucosa for 
 the engrafting of the fertilized ovum, that it is in fact, an essential 
 feature. This idea was promulgated when it was thought that the 
 ovum re(juired a connective tissue free from covering epitlKiliuin to 
 become engrafted on. I have repeatedly urged its improbability on 
 the followinjj orouiuls : 
 
 a. In all mammalians below homo, .so far as is known, the ovum 
 grows in relation to the epithelium-covered uterine mucosa and does 
 not reijuire a coiniective-tissue surface. The uterine ej)ithelium is 
 
i 1 
 
 undoubtedly uon-essontial, l»ut it is destroyed by degenerative pro- 
 cesses and by the troplioblastic action of the outermost layer of the 
 ffi^tal epiblast. As far as our oltservations go in human development 
 the same processes occur there. 
 
 h. Pregnancy may occur in a girl l»cfore the onset oF menstruation, at 
 a time therefore, when the mucosa cannot be denuded by that process. 
 
 c. It may occur fluring ti»e lactation period, long after the uterine 
 mucosa has been restored, and at a period in which menstruation is in 
 abeyance. 
 
 (I. It may take place in one of the periods of amenorrho-a during 
 the progress of the menopause. 
 
 ('. It may occur in periods of amcnorrhcea due to diseases <■. r/., 
 aneemia, phthisis. 
 
 / Clinical experience of ca-ses of pregnancy following a single 
 coitus proves that development of the ovum may l>egin at any time, 
 not nece.s.sdnly immediately after menstruation. (It must be stated 
 that this evidence is of doubtful significance, owing ^o the uncertainty 
 in our knowledge as to the time it takes the rvum to pass from the 
 ovary down through the genital tract and as to how long the sperma- 
 tozoa may live in the tract.) 
 
 g. Pregnancy may occur in the rudimentary horn of a malformed 
 uterus, menstruation never having taken place in that horn. 
 
 (Whereas, as P. MUeller points out, there is no recr -d of pregnancy 
 having ever occurred in the horn of a bicornuate uterus which is 
 atresic in its lower part ; menstruation goes on in it, as we know, the 
 blood accumulating above the atresia). 
 
 h. It may occur years after menstruation has ceased at the supposed 
 menopause. An interesting example is Renaudin's case in which a 
 woman of sixty-two was delivered though she had not menstruated 
 for over ten years. 
 
 i. In male pseudo-hermaphrodites, possessing testes but no ovaries, 
 the vagina, uterus and tubes may be present and menstruation may 
 go on regularly or irregularly. 
 
 Another view is to the effect that, along with the maturation of the 
 ovum, the endometrium swells as the first stage in the formation of a 
 decidua which will receive the ovum if it be fertilized. If fertiliza- 
 tion does not occur, breaking down of the superficial portion, the so- 
 called " menstrual decidua " occurs, and the menstrual discharge takes 
 place ; in this way menstruation may be regarded as the expression of 
 the failure of a proce.ss meant to be initial to pregnancy For, if fer- 
 tilization occurs, it is thought that the swollen mucosa advances to 
 form tlie decidua of pregnancy. 
 
This view, it is evident, is based upon a fallacious assumption, and 
 my objection to the last mentioned theory may be (|Uoted to refute it. 
 
 There is no proof whatever that changes in the mucosa accompany 
 maturation of the ovum, and the best evidence we possess regarding 
 the alteration in the uterine uuicosa tluring menstruation, viz., the 
 observations of Johnstone, Bland Sutton, Heape, Minot and Mendl 
 goes to show that practically only blood and small portions of the 
 lining epithelium escape. There is norikially no exfoliation of a layer 
 worthy the name " men.strual decidua." 
 
 I think this term is a bad (me ; it is to be clearly uuderst(X)d that 
 no change occurs in the connective tissue element . of the muco.sa dur- 
 ing menstruation, viz., enlargement of cells. This change only occurs 
 in connection witli the inHuence of a fertilized ovum. 
 
 Lowenthal has advanced .still another explanation. He believes 
 that menstrual Vdeeding is neither a physiological function nor an 
 accompaniment of one, but that it is due to iinuimerable repetitions 
 of an unnatural state of things, viz., the non-fertilization and death 
 of the ovum. He says that the swelling of the uterine muco.sa is the 
 result of the embedding in it of the last ovum discharged from the 
 ovary. If this ovum be fertilized the swelling mucosa goes on to 
 form the decidua of pregnancy ; if no fertilization takes place, tb.e 
 ovum dies, and as a result of this death a breaking down occurs in 
 the mucosa. He, therefore, regards the menstrual flow as having all 
 the characteristics and ettects of other bodily luemorrhages. 
 
 Lowenthal's view is a piece of speculation with(jut any factual 
 basis. No one knows anything about the unfortunate ova which do 
 not fulfil their highest destiny. It is a .sympathetic imagination 
 which makes them cling in their downward course to the walls of a 
 rept:llant uterus, forcing changes upon that oi-gan, in the fond hope 
 tliat a wandering spermatozoa may cleave to it in consunmiative union. 
 
 Fanciful also the picture of death following bitter disappointment, 
 the coincident decay of the dead ovum's re.sting place and the final 
 bearing away in a blood-red funeral stream of the fragments of a once 
 active individuality. 
 
 Johnstone believes that the simplest definition of menstruation is a 
 periodic wasting away of the corpuscles that are too old to undergo 
 the changes which must occur in connection with the attachment and 
 development of the fertilized ovum. He does not regard the endo- 
 metrium above the internal os as mucous membrane, but as belonging 
 to adenoid tissue. 
 
 Menstruation is for it what the lymph stream is to the lymph- 
 gland or the blood stream to the spleen. The development of the 
 
corpuscnldi' fU'iiH'iits, lir thinks, takt-s pljici; in the ciKloinctriuiii, us in 
 tilt' l»ltKMl-;;liin(lM, spleen, tliyioid, etc. 
 
 The exi.stencL* of nien.stnmtiun in tlu> liunmn iVnuile and its aliscnci' 
 in tlie iiDininialian onlerH hclow tlit* Prinintes, htM-xplaiiiH liy postnml 
 ilitf'erences, and l»y ditierence in the striu'tiiri' of the endometrium. 
 From his studies he is of tlie opinion " that nature has supplied the 
 endometrium with an altundnnt lymph stream, which in the iuiimpr< i>- 
 nated state washes away the riptf mattu'ial to the j>i'neral circulation 
 exactly as it does any other lymph corpuscle. I hit in woman, where, 
 on account of its erect position, the utc^rus has todt-pend on tlu- 1< nacity 
 of its own tihres for the preservation of its shape, no such thinj,' as 
 loo.se tissue of a lymphatic network can he depended upo?i. So, to 
 prcaei'vc the inte^n'ity of the uterine wall, the ennd^ent stream is 
 poured into the cavity of the liody,and ^ot rid of throu<,di the va<;iua. " 
 
 5. Rt'btt'ion to Hod 11 Mt'tdhoi'isiii. — (Jeddes and Thomson in their 
 " FIvolution of Sex " have advanced the theory that the menstrual 
 process is related to the balancing' (jf anabolism and katabolism in the 
 female or^'anism. 
 
 After puberty a surplus is produced in the .system because the 
 anabolic preponderates over the katabolic. When prej^nancy occurs 
 this excess is spent in the nutrition of the ovinn ('urin^^ its parasitic 
 intra-ute)'ine life and durini,^ lactation. When the.se methods of using 
 the analtolic surplus are wanting, menstrual losses occur in order that 
 it may be got rid of. 
 
 lilolof/iciU donrnde/i'dt'ions. — Scarcely any attention has been given 
 to the consideration of menstruation in its biological a.spects. 
 
 The speculation of the distingui.shed liiologists, (ieddesand Thomson, 
 is one of the most .suggestive which has yet been advanced, and it is 
 woi'thy of an elaborate study. 
 
 The careful investigations of many forms of plant and animal life 
 by zoologists and botani.sts, have enabled the biologist to establish a 
 distinction between " malene.ss " and " fenialeiie.ss " not only in torms 
 of morphological characters but of p.sychological and physiological 
 reactions. It is only recently, however, that .sex differences have been 
 investigated on these more subtle and difficult bases of in((uiry. Too 
 long have reproduction and sex l)een considered by themselves as if 
 they were .something to be disassociatetl from the general physiology 
 of the organism. 
 
 The mo.st important sex-distinction which has been established is 
 that which has to do M^itli the general metabolism, or protoplasmic 
 chemistry of the body. Every living cell and every organism is con- 
 tinually representing two forms of metabolism : one, the anabolic, by 
 
' 
 
 wliirli iiutritiiiii is tuktii in, wiistt- n'piiircd, cnfrjry Htoinl, structuif 
 iinpi'DVfil or altfrcil ; tlx- otlicr, the katnlxtlic, liy which |)<)tfiitial is 
 (!haii;;f(l into kinrtir fui riry ami inoVfiiirrit or activity inaiiit'»'sto<l, 
 striiftinal alterations indiicfd and wasti- cit-att'd. 
 
 'rhrou<^diont tin- aninud kini;doni the ilistinctivc and predominant 
 (diaracteristics ii\' the main sex is kataliolism and of the t'emales, ana- 
 liolisni. 
 
 (lenerally speakin";', the males show activity, contiinial expenditure 
 ol" ener;;y, disrn|ttive metaliolism ; the t'emi'les, passivity, i|uiescence, 
 (Mtnstructive metal lol ism. 
 
 The same distinction is also found in the plant worM. The lino.s of 
 ini|uiry <>n which this <feneralization has h»,'en injule are the followin}^ : 
 
 1. A study of sexual characteristics in the fully developed state 
 and in the history of the individual. 
 
 2. An investi<fation into the condition of the lowest t'ormsof animal 
 and plant life, wheie sex has its liei^inninu. 
 
 '.i. ()l)servation of normal antl patholoi^ical chanjfes in the reproduc- 
 tive ap[)aratus. 
 
 4-. E.Kperiniental in(|uiry into the nature of the factors which deter- 
 mine .sex. 
 
 J)etails rct;ardin<,' these lines of research are heyond the limits ot 
 this paper, yet some reference nmst he made to them. 
 
 As repii'ds the differences found in the ndult forms in the inverte- 
 brata and amoni;' Hshes, it may he stated that in ^^eneral the hody 
 temperature is lower in the female. ('I'his is so in many plants). 
 Their lon<;evity is <(reater. They are in ecmTul larecr and more 
 slugi^ish in habits. The males expend energy more freely, thus pre- 
 venting^ stora^u'e-accunndation and inci'ease in size. Amonn- bii-ds 
 anil mammals, while the jjf; neral metabolic diflerences (ixist the males 
 are usually larger than the females owing ttj special factors which 
 have come into operation and which do not exist in tht; lower orders 
 of life. Darwin and ( ieddc^s have explained thes(.'. They show that 
 the dirt'erences in size in tlu' higliei- forms are mainly in bones and 
 muscles. This is explained partly by the extra stress ami strain 
 thrown on the males while the females are in a state of pregnancy 
 and caring t'oi' the young ; partly by the strengthening ett'ect of tights 
 between the males, the strongest tending by natural selection to per- 
 petuate their kind ; partly by the effects on tlu; female con.stitution 
 of the excessive reproductive demands found among the higher 
 animals. 
 
 The distinction between the sexes is universally marked in the 
 .spermatozoon and ovum, the former being small, active, energising 
 
8 
 
 katabolic ; the latter , large, passive, highly nourished, anabolic. 
 While the metabolic differences between male and female have been 
 mainly studied in plants and the lower animals, some work has also 
 been done in the human subject, though here the difficulties are 
 greater owing to the greater complexity of the organism. 
 
 Blood — The red corpuscles are more numerous in the male, and the 
 percentage of haemoglobin greater than in women. The specific 
 gravity is the same until puberty. Afterwards it is higher in men 
 tiian in women during the se.Kual life. In old age it is usually higher 
 in women. 
 
 It is thns evident that the menstrual life is associated with a fall 
 in the specific gravity of the blood. 
 
 Pulse rate. — The pulse rate is slower in men than women. This 
 holds good for nearly all aniinals. 
 
 Respiration.— -Men produce more carbonic acid than women as 
 estimated by the breath. After puberty the amount is nearly double 
 that produced by women. It increases in the latter during pregnancy 
 and after the stoppage of menstruation. 
 
 Excretion.. — The ui'ine of women is usuall}^ lighter in colour than 
 that of men, and its specific gravity lower. The amount of urinary 
 solids is both absolutely and relatively less than in the case of men, 
 especially during the reproductive era of her life. 
 
 It is highly probable that those features which we call secondary 
 sexual characters, e.g., richer pigmentation, excess of hairs and feathers, 
 activity of scent glands, etc.. which are found in the males are but the 
 multiform expressions of the katabolic prudominence in the male 
 organism. And it is important to note that in the great run of cases 
 these characters are fully developed as maturity is established. In 
 early life there is practically no physiological distinction between the 
 sexes. The establishment of the reproductive functions is associated 
 with the development of sexual features, which, as Dai'win has 
 pointed out, modify the males to a much greater extent than the 
 females, throughout almost the entire animal kingdom. " Generally," 
 he states, " the female retains a cl<iser resemblance to the young of 
 her own species than to other adult members of the same group.' 
 
 Experimental evidence regarding the influence of various conditions 
 in the production of sex, points also strongly towards the conclusion 
 that " in the determination or sex, influences inducing katabolism 
 tend to result in the pj'oduction of males, as those favouring anabolism 
 similarly increase the probability of females (Geddes and Thomson). 
 Poor or abnormal food, deficient light, moisture, exercise, excessive 
 lactation and other conditions tending to diaiiuish the repair-supply 
 
or to cause a surplus of waste — the katabolic habit, tend, in experi- 
 ments made on lower animals, to the production of males. Such tests 
 strengthen the view that the male is the index of a preponderating 
 katabolism, and the female of an equally marked nnabolism. 
 
 Now, throughout the greater part of the anin)al kingdom, this 
 anabolic predominance in the female affords the means of counteract- 
 ing the katabolic inHuence of the part she has to play in reproduction. 
 
 During the sexual life of females among most of the Primates, the 
 anabolic habit does not Hnd sufficient employment in supplying this 
 destructive influence. An overplus exhibits itself in the production 
 of milk during the early perio<l of the child's life, and, after lactation, 
 in a discharge of blood from the uterus. 
 
 Cases of menstruation during lactation might by this theory be 
 easily explained. The production of milk does not use up the ana- 
 bolic surplus, which, therefore, becomes disposed of through the sexual 
 menstrual outlet. 
 
 In all mammalians below the primates the balance is regulated 
 without the occurrence of any loss through menstruation ; reproduction, 
 lactation, the care of the offspring and their moving habits apparently 
 making such demands upon the maternal anabolism that no surplus 
 corresponding to the menstrual blood of th': human female is pro- 
 duced by the system. 
 
 (In the vegetable kingdom, also, it is interesting to note, " the dis- 
 tinctly anabolic overffow of nectar ceases at fertilization, and the 
 surplus of continual preponderant anabolism is di-afted into the gi'ow- 
 ing seed or fruit." — (Jcddes and Thom.son.) 
 
 One of the most striking characteristics of menstruation, as observed 
 in the human female, is its variability in type, and in the <|ua:itity 
 and duraticjn of the discharge. 
 
 One need not specify these in detail. I wish in particular to diiect 
 attention to the great range of variation in the time of its appearance 
 in relation to the development of those other phenomena which we 
 call the " sexual characteristics." 
 
 In the majority of cases these features e. g., activity in ovulation, 
 menstruation, hair-development, growth of bi-easts, etc., become estab- 
 lished at a definite period, known as puberty, which, as we know, 
 varies according to climate, race, environment and other conditions. 
 
 But of far greater importance are the variations which prove that 
 tfiere may be no concurrent inciderce in the determination of the 
 phenomena in the individual. They are as follows : 
 
 I. Menstruation nuiy begin vi-ry early in life, even within the finst 
 year, without the development of any of the other outward signs of 
 
10 
 
 puV)LTty. The«e become marked, at varying periods in different cases, 
 and in diffei'ent urdei's. Generally, tliey appear together after a 
 numJ)er of years, but sometimes the bi-east changes precede the others, 
 souKitimes the growth of liair, sometimes the changes in bodily 
 contour. 
 
 2. In other cases, the development of nienstruation at a very early 
 period may V>e associated with one or more of the other secondary 
 sexual characteiistics. Thus the breasts may be well-marked, or the 
 external genitals ■>vell-d<;v(doped, or the voice altered. The other 
 features appear in later years. 
 
 8. In other cases some of the secondary sexual characteristics other 
 than menstruation may be developed in very earl}' life, this function 
 becfjniing estalilished sooner or later afterwards. Thus the breasts 
 may become well-markcid, mensti'uation following after months or 
 years. In a case recorded by Bouchut, in which the birasts were 
 well-formed at birth, menstruation began at the age of 22 monthS) 
 and the rest of the sexual features became marked in the succeeding 
 2 years, so that at the age of 4 years the child had all the characters 
 of a fully developed girl. 
 
 Somt^times the breasts and external genitals may develop early 
 together. Somiitimes the latter alone may be very early marked, 
 Vjeing followed sooner or later afterwards by menstruation and the 
 other phenomena. 
 
 Sometimes the buasts develop early along with axillary and pubic 
 hairs, being followed after wionths or years by men.struation. 
 
 Sometiiues the body-contour may I'esemble the adult form, the hair 
 and external genitals lieing well developed, at a very eai'ly period ; 
 the appearance of menstruation and the growth of the breasts being 
 delayed for months or years. 
 
 4. As regards the condition of the internal genitals, only a few 
 opportunities have presented theui.»<elvi.s of observing them in the 
 above-cited cases, so that it is impossible to know in how many 
 ovulation was in ])rogress oi* the utei'us well-developed. It is, how- 
 ever, clearly established that in some of these precocious cases ovulation 
 is in progress and the uterus with adult features There can be no 
 doubt, therefore, that pulterty may be completely developed in the 
 first years of life as regai'ds the physical changes. As is to be ex- 
 pected the psychical alterations are wanting. 
 
 5. Finally, tlie cases must be alluded to, in which during infancy 
 and child life, ovulation has been noted, though none of the other 
 signs of puberty have been present. It has been found in progress 
 even before birth. In the great majority of cases of noimal develop- 
 
 nmtmmlmmm. 
 
11 
 
 inent of puberty, it may be in progress several months before the other 
 plienoniena appear. 
 
 In the adult state marked variations are found as reganls the degree 
 to which the sexual characters are developed. 
 
 These need .scarcely be specified, so connnonly are they ob.served by 
 phy.sician.s. 
 
 They affect the breasts ; the pubic and axillary hairs ; the formation 
 of the external genitals ; the type, ([uantity and duration of the men- 
 strual discharge ; the psychical development. These diflerences exist 
 between different races and between the various members of the same 
 race. 
 
 From the consideration of the many facts to >vhich I have referred 
 we are forced, it seems to nie, t(j I'egard the menstrual function as a 
 highly .spedalised means, gradually produced, in the evolution of the 
 highest mammals by which the two great factors in tissue metabolism 
 — the anabolic and katabolic, are propei'ly balanced. 
 
 Normally it becomes established along with the various phenomena 
 which characterise the development of sexual activity — at puberty, 
 because it is then thai the metabolic hal)it peculiar to females, viz., 
 predominence of anabjlism manifests itself. 
 
 The rythmical chai acter of the menstrual function has probably . 
 been gradually determined by the foi'ces of evolution, and the marked 
 i-ange of variations which it presents in the human female (unasso- 
 ciated with pathological conditions) points very strongly to an early 
 period oi instal)ility in the pi'ocess, preceding its present fjiirly fixed 
 habit. It is, indeed, impossible for us to thiidc of a rational explana- 
 tion for the peculiarities which are found except on the ground of 
 biological vai-iations — atavistic reminiscences. 
 
 The menstrual function, then, being closely correlated with the 
 well recognized sexual cliaracters is, like them, undoubtedly closely 
 related to a nervous regulating mechanism, th<; nature of which is 
 unknown as yet. There may be a special cord centre governed by 
 still higher cortical centres, but there is also a subtle and intimate 
 connection l)etween the sexual functions and the general nervous 
 mechanism of the l)ody. 
 
 As Johnstone ably states in regard to the uterus, " its association 
 witii ovarian activity is that of two separate departments of an army, 
 each of whose work must be thoroughly accomplished before the one 
 common object can be attained. The}'^ are both controlled by branches 
 from the sympathetic S3'stem, and instead of their actions being 
 determined l)y each other, their orders come from that higher power 
 which controls all functional activity." 
 
12 
 
 It is this correlation which has been wrongly interpreted, especially 
 in the case of the tubal and ovarian functions, with neither of which 
 is the process directly connected. That it is indirectly related to 
 them and capable of being influenced by them cannot be denied, and 
 that of the whole sexual apparatus the ovaries are the " predominant 
 partner " is not to be wondered at. We have proofs enough as regards 
 their influence on body-metaboIisTu, e. q.. in osteomalacia, marked 
 improvement immediately follows removal of the ovaries. Whether 
 this be due, as Curatiilo believes, to the secreti<m by these organs of 
 a chemical substance capable of facilitating the oxidation of t'.^e phos- 
 phoric organic substances supplying material for the bone salts, or, 
 whether it acts merely by altering an ill-proportioned relationship 
 between anabolic and katabolic functions, thus secondarily affecting 
 the diseased proces-s, is only a matter of speculation. 
 
 After the removal of the ovaries in gynsecological practice, certain 
 effects are noted, which must be associated with altered neuro-trophic 
 functions. Thus " heats " or " flushes," va.so-motor storms are very 
 often troutilesome features. The uterus tends to shrink, the gland- 
 tis,sue of the breast tends to atrophy, while fat is often increased in 
 the body. There is. however, very great valuation as regards the 
 .effect of removal on the sexual characters. These are so marked as to 
 demand a careful investigation for the purpose of determining them 
 accurately and of establishing a comparison between the bodily 
 changes following the operation and those taking place in connection 
 with the normal climacteric. At present many exaggerated ideas are 
 current. 
 
 While, in the majority of cases, removal of the ovaries is followed 
 by an altered body-metabolism owing to the absence of the mo.st 
 inipoi'tant sexual organ, marked by tlisappearance of the anabolic 
 overflow of menstruation, it is not surprising that variations should 
 occur in the alterations produced, so that instances might occur in 
 which the menstrual function does not cease. It is certainly not an 
 uncommon experience to find discharges of blood from the uterus 
 after the operation, apparently, an indication that the changes in 
 body-metabolism are being brought about but gradually in these cases. 
 
 As regards the relation of the tubes to menstruation, if Lawson 
 Tait's observations be accurate, viz ; that after their removal vaenstru- 
 ation ceases in the great majority of cases, the ovaries being left 
 behind, the explanation may be, either that such a marked alteration 
 in the genital tract may reflexly alter all the sexual functions along 
 with body-metabolism, or that it may bring about the result through 
 an indirect influence (such as inhibition of function) on the ovaries. 
 
18 
 
 Bland Sutton's statements as regards the effects of removal of the 
 tubes are directly opposed to those of Liiwson Tait. His words are, 
 " the Fallopian tubes exercise no influence on menstruation, and in 
 order to produce artificial amenorrh<j'a both ovaries must be com- 
 pletely removed." I do not consider that Bland Sutton is justified in 
 making these statements from the facts given l)y him. He quotes a 
 few cases in which ligature of the tubes was performed without caus- 
 ing a ce,s.sation of menstruation. Tait, however, speaks of removal of 
 the tubes, a much more serious disturbance. 
 
 Though there can be little doubt that menstruatioi has been estab- 
 lished in the higher maunnals by a gradual process of evolution, we 
 have been entirely in the dark as to the steps of this process. Seeing 
 that it is limited to the anthropidai and .simiadai, the earliest appear- 
 ance must have taken place among some common ancestors of Vjoth. 
 
 The peculiarity probably first began as a variation, which proved 
 to Vie advantageous and V)y natural selection became a fixed character, 
 being transmitted from generation to generation. Had it been of no 
 advantage it would have been eliminated. 
 
 The only suggestion which has yet been advanced as to the possible 
 advantage of this variation is that of W. E. Fothergill, who believes 
 that it consisted in a greater tendency to conception owing to the 
 rawing of the uterine muco.sa. 
 
 This suggestion cannot be entertained in the light of present know- 
 ledge. We know that rawing of the surface is not necessary to the 
 attachment and nidation of the fertilised ovum and that in the great 
 mass of the mammals it does not occur. 
 
 The introduction of menstruation in the evolution of the mam- 
 malians has not been associated with greater but with diminished 
 fertility, for there can be no doubt that the non- menstruating mam- 
 mals are on the whole by far the most prolific. 
 
 Indeed, natural selection, has acted in the highest ranks of the 
 animal world not in the direction of establishing a numerical super- 
 iority, but one based on the specialisation of individual characteristics 
 in a selected number. 
 
 The advantage of the variation in our distant progenitors must 
 therefore be sought for in relation to factors ten' ling to diminish the 
 number of oflTspring and to improve the quality of the individual. 
 
 As to the origin of the variation, the only reasonable speculation 
 seems to be that it is associated with the development of the single 
 uterus, with the diminution in the number of oftspring, with the 
 determination of the semi-erect or erect po.sture, characteristics found 
 throughout the Primates, at least in the simiadir and anthropida'. 
 
14 
 
 (The division of th(^ Primates, known as the leinuridje, stands by itself. 
 These forms are believed not to be in the direct line of the other 
 divisions but a separate offshoot from nome early common mammalian 
 stock. They have a double uterus and, so far as we know, do not 
 menstruate.) 
 
 or prime importance I believe , amon<; these i'actors is the change 
 from the bicornuate to the singk: condition of uterus. In the great 
 mass of mammals with tlie former variet}*, the exces3 of anabolism is 
 used up in the large demands of breeding and nunsing. When the 
 single uterus appeared as a variation marked by a diminished area for 
 the attachment of ova, the unu.sed anabolism found an outlet in the 
 escape of blood. 
 
 It is possible that this took place at first from different parts of the 
 body thus helping to explain the occasional occurrence in females of 
 " vicarious menstruation." 
 
 If this were the case, natural selection must have acted in eliminat- 
 ing all except those in whom the blood escaped from the i.terus. 
 
 But it is also likely that the tendency to sit on the ischial tuberosi- 
 ties and to move about mi^re or less in the semi-erect position may 
 have somewhat determined tlie occurrence of the congestion chiefly in 
 the pelvis, relief being found by a discharge from the delicate mucosa. 
 
 The blending of two blood-supplies in a single uterus, which had 
 previously been distributed to two cornua, must have had an influence 
 in inducing a special tendency' to uterine congestion. 
 
 ProbaV)ly also another factor helped to determine the localisation of 
 the congestion to the pelvis, viz: the habit already fixed among many 
 of the lower mannnals of the periodic pelvic congestion of the rutting 
 period. 
 
 In the beginning it is likely that the menstrual discharge took place 
 at irregular intervals (thus explaining the occasional irregular types 
 which are now found among females.) 
 
 Natural selection would here come into play in determining regu- 
 larity of type. 
 
 Females who were irregulai- in regard to the discharge would be 
 objects of inconvenience to the males who would very soon learn to 
 seek out and prefer those who.se unseemliness manif(!sted itself onh' 
 at expected and definite periods, and so gradually regularity would 
 come to be the predominent feature in succeeding generations of off- 
 spring. 
 
 It is » striking fact that among all races there is a careful avoid- 
 ance of menstruating females by the males. This is particularly 
 marked in most pi-imitive peoples. Very possibly it had its origin in 
 
 I? 
 
 If 
 
15 
 
 f 
 
 Ilif 
 
 If 
 
 a feeling of disgust on the part of the males, and it is noL difficult to 
 understand how among the earliest human heings, there might grad- 
 ually develop the helief that women were possessed of some unclean 
 or evil spirit which had to escape periodically. 
 
 It i^^ thus easy to explain the universal though varied customs and 
 practices prevalent in numy races, by which the woman is forced at 
 hor periods to avoid association with others, to abstain from coitus 
 with men and to withdraw even from observation in order that her 
 evil influence might not spread. 
 
 Next, it is of great int -rest to in(|uire into the pos.sible gains that 
 might result from the fixing of the menstrual process in females. 
 
 It is a remarkable fact that in the highest mammals, viz : the 
 simiada? and anthropidte, is found the highest development of the 
 altrui.stic principle as exhibited between parents and offspring. As 
 We.stermarck points out, among the invertebrata the male is interested 
 only in the act of fertilisation, while the female shows no further con- 
 cern or responsibility after she has laid her eggs. In the lower verte- 
 brata parental care is almost unknown, though there are a few excep- 
 tions, e. <j., chiefly in tln' chelonia ; the males caring foi- the ytnmg in 
 some ca.ses, the females in others, while in a few instances there is 
 joint parental attention. 
 
 In the birds, however, it is the rule that the parents live in most 
 intimate relationship, both during and after the breeding season, the 
 female hatching and rearing, the male acting as protector and provider 
 of food. 
 
 Among the great mass of mammalians, below the primates this is 
 not the case ; the mothers alone showing great concern for the young 
 offspring while generally the males ai'e only interested in the females 
 at the rutting time. 
 
 Exceptions are, howevei', found c. [/., among whales, seals, certain 
 deer, moles, s(piirrels and a few other forms ; the parents remain 
 together after the birth of the young, the malt- acting as protector. 
 
 Among the Primates the rule is that the males and females unite 
 in a more or less enduring partno'ship, both having great concern for 
 the care of the offspring, the males posse.ssing one or more wive.s. 
 There is an abundance of facts to establish this statement and from 
 them Westei'marck has established his induction in a masterly work, 
 that our human marriage is an inheritance from an ape-like ancestor, 
 controverting- the lon;j- lieM belief of Sir John Lulibock and others that 
 our progenitors formed one vast free-love community where promis- 
 cuity of sexual intercourse prevailed. 
 
 This habit is therefore another interesting posssession of mannnals 
 
16 
 
 I 
 
 with a single uterus. It marks a jjreat advance in the character of 
 the individual alx)ve the types found in the lower orders of animal 
 life. 
 
 Very evidently it was fostered by means of natural selection, being 
 most essential where the fcMnaln gave birth to a small number of young 
 'vho passed a long time in a state of helpless infancy and tutelage. 
 Such a species, undoubtcsdly, stands a better chance of .surviving when 
 the parents unite their energies in the task of protecting and nurtur- 
 ing the offspring. 
 
 Indeed, it would appear that the great determining factor of con-' 
 jugal relationship is care for the young. Among several primitive 
 races (and in some of the highest) marriage is never supposed to be 
 established until offspring appear. 
 
 Wherever in the animal kingdom we find that the parents have no 
 concern with their offspring, the females give birth to a very large 
 number of offspring — th(; prodigality of births allowing of the safe- 
 guarding of the preservatioi> of the species. Thus the cod lays each 
 year about a million eggs, to which she gives no after-care, and, 
 probably, the greater number become destroyed. On the other hand 
 the turtle-dove lays only two >>ggs, but owing to the care which the 
 parents give to the young they generally grow to maturity. 
 
 Another important point to notice regarding intercourse between the 
 sexes, is that while among the majority of mammals there are special 
 times of pairing, conditioned by various necessities, different in differ- 
 ent species, among the quadrumana the rule is probable that fruitful 
 intercourse may take place at any time, though undoubtedly excep- 
 tions occur owing to conditions of food, environment, etc. In the 
 evolution, therefore, of the higher mammals possessing one uterus, 
 there has been a departure from the condition of periodic excesses of 
 sexual rioting to one in which there is especially in the female, a more 
 diffuse and consequently less intense manifestation of the sex instinct. 
 
 The menstrual function occurring regularly in animals so placed, 
 must have served beneficially in giving the mothers continually re- 
 curring periods of ensured rest (for so far as we know coitus is uni- 
 versally desisted from during menstruation) and in teaching the males 
 continual lessons in self-restraint. 
 
 Relation of Menstruation to Rut. — There is a wide-spread belief 
 that these phenomena are identical. Thus a very recent writer 
 (Letourneau) states that " menstruation is essentially identical with 
 the intimate phenomena of rut in the females of mammals and corre- 
 sponds to an ovarian congestion, or to the swelling and bursting of 
 one or more Graafian follicles. A few writers have in recent years 
 
 ;:| 
 
M 
 
 > 
 
 IT 
 
 disputed this viow, among whom may be chioHy mentioned Lawson 
 Tr't 
 
 There r.re many who believe that the rut or (J'strus, or pairing time, 
 is conditioned by ovulation — tiuit ova are only shed at these intervals 
 causing the phenomena. There is no basis of facts for this statement. 
 The examination of many rutting animals proves that ovulation goes 
 on at all times. The origin and significance of rut are uncertain, but 
 it .seems probable that tin.' habit has l)eeu developed by natural 
 selocticm for tim purpose of limiting the chance of fertilisati<m to 
 certain seasons iiiainl}- with reference to dietetic and climatic re(|uire- 
 ments for the oH'spring. 
 
 Among the mammalians this period v., found at all times of the 
 year. ' Thus, the bat pairs in January an<l February ; the wild cat and 
 lo.K in February ; the wea.sel in March ; the irmsk ox in August ; the 
 badger in October ; the orongo-antelope in November und December. 
 
 When the different cases are encjuired into it will be found that the 
 time of pairing is related to the duration of pregnancy, it being neces- 
 sary that the young should be born at a tiuje when they stand the 
 best chance of living. 
 
 Thus the majoi-ity of maiiuials produce offspring early in the year ; 
 in the tropics at the beginning of the rainy season— the time of birth 
 evidently being related to abundance t)f food, water, warmth of 
 climate, conditions most favourable to existence. In polar and tem- 
 perate regions the animals pair at a later period than in warm coun- 
 tries. These differences are seen when the same species are placed 
 under different climatic conditions. 
 
 When no definite pairing .system exists, as among elephants, whales, 
 many rodents, the explanation is very evident. The conditions of 
 their environment antl of their food supply are such as not to necessi- 
 tate the birth of offspring at special times. 
 
 Among the primates it is doubtful if there is a rutting season among 
 many species. It is stated by .some observers that it exists in the 
 orang-outang and gorilla. In general it is to be expected that in the 
 simiadse and anthropidae, whose food supply is of a much more diverse 
 nature than in the lower mammalians, consisting of animal and vege- 
 table matter in different forms, there is no necessity for the birth of 
 offspring at special times. Moreover, it must be remembered that the 
 anxious time as regards the newly born does not last only for a few 
 months after birth in the simiadae, but for years, the period of infancy 
 being long just as in the case of homo. It is therefoi'e likely that as 
 far as food reijuirements are concerned one season is as propitious as 
 another for birth. 
 
18 
 
 Another important factor must he home in mimi, viz : that where 
 there is a strong development of p trental atiection and conjoint j)ar- 
 ental care for the young, an important additional reason exists for 
 diminishing the necessity of special pairing seasons. This is all the 
 more marked in tlu? anthropidie where, owing to a higher intelligcsnce, 
 individuals learn to combat the injurious inHuences of their (inviron- 
 ment and to make it possible for the offspring to have; as good a 
 chance of surviving at one time of the year as at another. 
 
 If then, there be found exceptional eases of special pairing season 
 among the higher primates, it must be becau.se tiatural selection has 
 conserved the habit in relation to the special conditions in which tho.se 
 species are placed. 
 
 Among the reptilians and birds, the rule is that pairing occurs in the 
 spring, and it is probable, that, as Westermarck points out, the vvorld- 
 witle association of the springtime with tht; awakening of sexual 
 affinities has been based upon the observations uuide mainly on birds. 
 
 The modifications in the pairing season which can be induced by 
 artificial means, e. g., domestication, are a strong evidence in favour of 
 the influence of external influences (m reproduction among the higher 
 vertebrata. Indeed, it is evident that just as rut becomes adapted to 
 the requirements of separate species, so it may become; altered in 
 relation to the needs of individuals under varying conditions. 
 
 Another interesting fact must be mentioned viz : that while the 
 rutting-period is practically the only time when the females will 
 copulate with the males, the menstrual period is the time above all other 
 periods when they will not engage in this act. This is universal among 
 mankind and is true for the siiniadfB as far as our observations go. 
 
 Moreover, the changes in connection with rut result among other 
 things in .softening antl dilating the outer genitals for the reception of 
 the penis, they being at other times in many animals too much con- 
 stricted for this. It is well-known that a bitch will not generally 
 allow the dog near her until the rut has been in progress for a time, 
 i. e., until the vulva and vagina are sufficiently dilated. ' 
 
 So fares our facts go, it seems likjdy that rut in the higher verte- 
 brates is merely the expression of the force of sexual affinity necessary 
 to ensure fertilisation of the ovum, which is found throughout the 
 whole animal kingdom, diffusely spread in the lower forms, highly 
 specialised and limited in the upper forms owing to the influence!? of 
 environment and natural selection, and affecting both males and 
 females alike. This participation of the males is important to bear in 
 mind. It is found everywhere. Thus many fishes when the love 
 period arrives put on brilliant colours, become vigorous and play about 
 
 f 
 
r 
 
 
 I!) 
 
 aiiion^ i\w fuinaleH in the iiioHt lively fashion — cvidt-ntiy in a state (»t' 
 H«'xuiil I'xciteint'nt. In some, e. g., the stickleback and salinon ^rcat 
 pii^^'iiac'lty is nianit'cst. The male salmon (lev«'lops a special crook in 
 connection with the lower jaw at this time, while the teeth enlarj^e, 
 markedly, Ainon;,; many amphihiaiis also many chanj^es atl'ect the 
 males, sexual desire hecominj^ very marked. Amon^' the reptilia similar 
 chan;^fes occur, the male tortoise for example heinj; fierce and noisy. 
 In snakes the scent-j^lands become active during the pairiii^-.sea.son. 
 
 Amoiii; the hirds the chanj^es in the lovesea.son are very marked. 
 The male is altered in variovis ways and takes to dancing, co(|netting 
 and to vocal and instrumental music. His scentj^lands jjrow active ; 
 his ornaments become more marked, and he developes stroiij; Hj^htinj; 
 tendencies. 
 
 Amonfj mammals the intensification of sexual desire in the males, 
 accompanied with a feeliii}^ of jealousy and a keenne.ss to fight, is 
 universal. In all orders the voice is used in the rutting-time more 
 than in any other sea,son. Indeed, the porcupine anrl giraffe are said 
 to be mute at all othei* periods. In stags the larynx and thyroid 
 enlarge when rut comes on. The nose of the male sea-serpent becomes 
 greatly enlongated. In the bladder-nose seal the hood c<jvering the 
 head becomes markedly inflated. Scent-glands emit strong odours. In 
 some cases the colour of the skin changes. Amonfi the ffreat majoHti/ 
 of females ni nuch marked changes occur. They play their normal 
 role of passivity, the changes brought about by the wave of sexual 
 excittiment being mainly psychical. 
 
 In many mammalians the only physical changes recognizable at the 
 cpstrus are congestion of the soft parts in the pelvis, dilatation of the 
 vulva and the vagina, and the free discharge of mucus which is often 
 blood-stained. These differences between males and females in regard 
 to the rutting period are in keeping with the organic distinction to 
 which I have so often referred in this paper. 
 
 The manifold changes in the males are the outcome of their pre- 
 dominant katabolism. 
 
 The females need to con.serve their energies i.e., their anabolic 
 surplus, for the strain of pregnancy ; consequently then; is no waste 
 in outward exuberant manife.stations, except in very slight mea.sure 
 in the cases to which I hnvv just alluded. 
 
 Finally, it may l)e stat(;d that the relation of rut t(i menstruation 
 in mammalian evolution is simply this — chat when, owing to the 
 various I'easons which I have elaborated in an earlier ])art of this 
 paper, menstruatini appeared as a new variation, una <jf the factors in 
 deterujining the escape of the anabolic overplus by way of the genital 
 tract was the haliit already Hxtxl, in many of the mammalians with a 
 bicornuate uterus oi the periodic yearly pelvic congestion of the 
 rutting time.