Materials for the Study of Variation Treated with Especial Regard to Discontinuity in the Origin of Species

Fully formed supernumerary mamma; have been found above the normal mamma- and also Kelow th.-m, the latter being the mopfrequent position. For those found on the mammary lines tinaxilla is tinhighest position and the upper part of the abdominal wall the lowest. Of the rudimentary forms, the mammary tumours \\ithoiit nipples occur usually if not always above and external to the normal mammae, being generally in or near the axilla. The supernumerary nipples however are in the great majority of i asee helow and internal to the normal ones.

Small supernumerary nipples are quite common in Man, but the statistics »f different ol.serx.Ts give various results. Bruce found in -J::il females | 4 cases ( -CO.") per cent .). and in 164."> males 47 cases (2*857 percent.). These persons were patients at the hrompton Hospital for Consumption and were not specially examined with a view to this inquiry. Among '.}\~y such persons examined I'm- tinpurposes of these statistic-. 1^4 cases were seen (7'<; per cent.), 1!) being male and ~) female. In cS cases two extra nipples \\.-re pn-.-nt. and one doubtful case of three extra nipples

1 N.»t including mammary tumours \\itli. >ut nipples in tlu- a\ill:i . was seen. Bruce regards 7'6 as for various reasons rather too high a proportion. In a recent paper BARDELEBEN however states ih.ii among 2736 recruits examined with regard to supernumerary nipples, 637 cases (23'3 per cent.) were seen, 219 being on right side. 248 on left side, and 170 on both sides. The discrepancy between these statistics no doubt arises through want of agreement as to the inclusion of cases in which the extra nipples are very rudimentary.

It seems to be clearly shewn that the abnormality is commoner in men than in women, and there is some evidence that it is nx>r<' frequent on the left side than on the right (BRUCE, LEICHTEX- STERN and BARDELEBEN). It is also well established that supernumerary nipples are much more commonly present as single than as paired structures, and that when paired they are by no me;m- ahvays at the same level on the two sides. Cases of the presence of supernumerary mamma? as paired structures symmetrically placed are nevertheless sufficiently numerous. Organs of this nature may also occur simultaneously on the same side of the body at different levels. For example in one of LEICHTENSTERN'S cases, a small secreting supernumerary mamma with a nipple was present in the left axilla, while there was also another supernumerary nipple on the lower border of the left breast. The greatest number of supernumerary nipples occurred in a case described by NEU- GEBAUER1, represented in Fig. 29. In this patient there were on each side three supernumerary nipples above the normal ones, and

Fir,. 29. Diagram of a case of four pairs of supernumerary nipples in human female. The normal breasts raised to shew the lowest pair. (After NEVGEBAUER.) on i- "it ••:i<-li side below them. The latter were concealed by the pendent breasta When the child was being suckled milk oo/.-d from each of tin uppermost or axillary nipples, but from the n -maining MX Mipernumerary nipples milk could only be extracted l>v pressure. The flowing of milk from supernumerary nipples when tin' child is at the normal breasts, has often been observed.

A few references to cases exhibiting the several features above I4!>. l!itid ni|iple. the same on each lnva-t [plane of division not -peciM- dj. |)i VAI.. l>u Maiiielon et de -son aureole, Paris 1801, 1 .'id. Two nipples on the same areola, bilaterally symmetrical. The t wo nipples >tood in the mammary line defined above. TIEDEMAXX, Ztsch.f. Physiol, v., l.s:«, p. lid, Taf. i. fig. 3. I ;, i. Cases are given by CHAIKJOT and LE GEXDHE, Gaz. med. de Paris, Is* •"'!». p. 77-'!. in which an extra nipple was placed external to the n..riiial one mi the same breast. In one of these the extra nipple li.nl n. i areola Leichtenstern (p. 253) in quoting these cases, -peaks <>f them as instances of supernumerary nipples on the vaiue level as the normal ones, but this is not expressly stated in the original account, which does not, as I think, exclude the p.— iliility that the supernumerary nipples were above and external to the normal cues. Two functional nipples with separate areolae on the lett breast, which nevertheless was not larger than that of the ri-ht -ide. il,nl. The same authors mention another ease in uhich >uch a second nipple had no areola; the mother of patient Lted to ha\e been the same. See also SIXETY. Gaz. I/K:</. de Paris, l"vS7. p. :!I7 (full description and measurements). In this Case the Miperiiunierary nipple was placed below the normal one.

AI>/»-II<I. p. 40. The case is given on the authority of PRACKEL and tinthree nipples are said to have ken arranged in an equilateral triangle, the normal being above at the apex, and the two others at the same level be|o\v. The de scr i pt ion a lid t he figure accompanying it do not however justify complete confidence in this observation, and indeed the contributions of 1 'an 11 in us to the Miscellanea Curiosa contain so much of the marvellous that they >lioidd not be accepted without hesitation. The same may be ^aid of the case of jh'c nipples each having an areola quoted by PEROT and LAURENT, !>><•/. Sci. m«i.. \x\iv. p. r)i7,.v. v."Multi-

mamme." The authority for this case is a letter of HannaMis to llorrichius, dated Hi7">. 1 have not found any observation of this class ..f abnormality later than the seventeenth century, but it is of course quite pliable that cases may occur in which the nipples are distributed on the breast otherwise than along the mammary lines. o. Supernumerary mamma with nipple in axilla, LEICHTENSTERN, p. 245, and others. 154. Supernumerary mamma above and external to the normal ones. Numerous cases; see especially case of two bilaterally symmetrical mammae in this position, SHANNON, Dull. Med. Jour., 1848, v. p. 266, Jig. [figure repeated by AHLFELD, WILLIAMS &c.]; also similar case, QuiXQUAUD, Rev. photogr. des hop., 1870, p. 11).

155. Supernumerary mammae below and internal to normal ones: numerous cases, see LEICHTENSTERN, &c. In nearly all these the FIG. 30. Supernumerary nipples and mamma? of different sizes in human female. (After BRUCE.) supernumerary organs are close to the normal mammae. A few examples of such structures on the upper part of the abdominal wall are known, e.g., TARNIER in his edition of CAZEAUX, Traite de I'art des Accouchements, 1870, ed. 8, p. 86. In the male several such cases are recorded, e.g., BRUCE, J. An at. P/tys., xin. 1879, p. 446, PI. Examples of this kind in the female are shewn in Fig. 30 (after Bruce) and in the male in Fig. 31 (after Leichtenstern).

156. Mammary tumours in the axilla are described by CHAMPNEYS, Med. Cliir. Trans., 1886, LXIX. p. 419, as of common occurrence in lying-in women. These structures are of various sizes and without any nipple, pore, or duct. The secretion was obtained by squeezing the lump and oozed through the skin at the situations of the sebaceous follicles. In this manner both colostrum and milk were obtained, following each other as in the normal mammae. Similar observations in single cases have been made by man}r writers.

157. Redundant mammary tissue of this kind connected with, and thus forming an axillary extension of the normal mamma?, CAME- RON, Jour. Anat. Phys., 1879, xm. p. 149; also XOTTA, Arch, de Tocologie, 1882, p. 108. FIG. HI. S.M]" Miimi>'i;iry mamma; in the male, symmetrical and asymmetrical. important case of a man having two pairs of supernumerary mamma' ,,n tinmammary lines. There was a gradual diminution in si/r from the highest to the lowest, the latter being a little above thr level of thr umbilicus. Each pair was at the same level.

/•'(////• jtiiirs of superiiumrrarv nipples (ten in all) are recorded only in NI.I GEBAUER's patient, already mentioned. Three of the siipernumerarv pairs \vrrr above the normal ones, and the other pair brlow thrin. As srrn in Fig. ^!) the nipples of each pair did not stand in the case of each pair at precisely the same levels, and between those of the lowest pair there was a considerable difference of level, thai on the left side being at some distance below the normal breast, \\hile that on the right sidewas on its lower border.

In a fe\v cases the suprrnumrrary nipple js described as having perpendicularly below thr normal one. and it is likelv that such cases must be looked mi as exceptions to the general rule that the mamiiian lines converge posteriorlv; but it is not impossible that even in son f them the supernumerarv nipple might ha\e been found to be rather nraivr the middle line if this point had been specially inquired into. The foivgoing examples are given as selected illustrations of thr several facts, and for full lists ,,f cases the reader is referred to I he \\ orks alreadv ineiit ioned.

100. ( >t' supernumerary maimn;r placed in parts of the body other than tinmammary line sum,, mention must be made, though those of them tliat are authentic have no close bearing on the subject of Meristic Variation. There are firstly two often quoted cases1 in the Mi.^-i-11,1,,,-,1 Curiosa in which mamimu are said to have been present on the back, but as has already been remarked, many of the stories told in this collection are clearly fabulous, and this is especially true of the contributions of Paullinus. Both these records are given at second hand and the first case (Paullinus) is said to have been seen in 15(i I, more than a hundred years before the date of the account. Helbig's accounts of t liings seen by himself are generally trustworthy, but in this case he is onlv repeating what was told to him by a Polish noble about a woman seen in Celebes. There are no modern cases oil record. There is however indisputable evidence of the presence of a mammary gland 011 the thigh (especially ROBERT'S case; for references to several accounts of this see Leichtenstern, p. 255); on the cheek, EARTH, Arch. f. path. An,<it. u. Pliys., 188, p. 569; on the acromion, KLOB, Ztach. f. K. K. Ges. (/. Aerzte in Wien, 1858, p. 815; in the labium majus, HARTUNG, Ueb.eineu Fall von Mamma Accessoria, Inaug. Diss., Erlangen. 1875. In the two last cases the mammary nature of the gland was

proved by microscopic examination. In Earth's case of a mamma on the cheek the microscopical investigation did not give a certain result (q.v.). As Leichtenstern shewed, the case of inyuiw'il mamma, mentioned by Darwin and others, really related to Robert's case of a femoral mamma. In 1885, however, BLAXCHARD (Bull. S<><\ d'Anthrop., 1885, p. 230) stated that TESTUT had lately seen such a case and was about to publish an account of it, but this has not yet appeared (1892).

Most writers on the subject have accepted cases of supernumerary mamma placed (interiorly in the middle line. These are given by PERCY and LAURENT, Diet. 8ci. med., xxxiv., 1819, on. the authority of several different persons. One case was seen by themselves (p. 526), and in it the third mamma stood below and between the other, forming a triangle with them. In another case given on the authority of GORR£ there are said to have been a pair of extra mamma? below the normal ones, and a fifth between the supernumeraries. In view of the fact that many paired organs may by Variation occur compounded in the middle line, there is nothing incredible in these accounts, nevertheless there is, so far as I know, no recent observation of such an occurrence in the case of mamma?, and with the one exception (which is very briefly described), the accounts given are at second hand2. It is moreover not clear that the words used "au-dessous et an >n!/i?ii des deux autres" do not mean simply below and /w//w,, the other two. The case contributed by Gorre is nevertheless given in great detail

Before speaking of the bearing of these facts on morphological conceptions it is necessary to refer to some of the phenomena of - Williams (p. 235) quotes BARTELS, Arch. f. Aunt., 187'2. p. HOi'.. as alluding to such a case, but I do not think that the passage is meant to convey thi* meaning. mammary Variaii'-n in other mammals. In connexion with the Mm it in iv In- mentioned that supernumerary mamma he|,i\v and internal to the normal ones has been seen in Macacus and in Cercopithecus patas, SUTTOV J. B., Intern. Jour, of Med. 1889 \< VII. pp. •!'>'! and 2.~>:> ; in the Orang-utan, OWEN, i. A • iii. p. TMI. In many mammals the number of the - i- very inc"ii<tant even within the limits of species and tin- : n in such cases deductions may be drawn which

are at one.- in-truetive as to the nature of mammary Variation and lia\<- an -i pplica: ion to the morphology of Meristic Series in i M these 1 shall give examples taken from three species. The tir.-t i- that "f the cow's udder. Normally the cow has f..iir beats "f alioiit eijual size. Not nnfrequently there are six tent-, of which four anlarge and may be said in the usual parlance to In- the " normal " ones, and two are small and placed posteriorly to the ft h«-r-. A case of this kind is shewn in Fig. 32, II. Commonly tin - ,e no milk, but in many cases they have been

kii-iun bo do so. Their -ixe and position vary greatly ; sometimes the\ are placeil near the other teats as shewn in the figure, but I ha\. seen them very hi^h up, almost in the fold between the udder ami the thi^h-. Very frequently, however, there is only one extra teat making tr. e in all, .sin-h an extra teat being so far as I know, always on I' •• s,ip. ilium. n t\vn iirjiWs. I. The third teat is completely . I'Ht IMI the ri^'lit si,lr i* uiiiti'il with tin' second. (Tinlh«- t\\" is iiir.ii ri-.-tly rr]>ri"i.'iit.'il ;is u sharji line; there was no such t ileiiiui-cati,.|i ; die ^kiu heinu' MTV slightly ile]iri'sseil in this place.) II. ! the thinl 1'iiir Imili c.nni'leti •, . - pal

*1G2. one side of the udder. The sketch given in Fig. 32, I. was taken from a heifer having an arrangement intermediate between the condition with four teats and that with six. A.S the figure shews, on the left side there were three complete teats but on the right side the third teat was incompletely separated from the second. This third teat was joined to the seconcl for its whole length but had a separate pore. The animal which belonged to the St John's College Dairy Farm was unfortunately sold before the first call' was born, so 1 had no opportunity of seeing whether milk was given by both these teats. The significance of such a case will afterwards appear.

In many mammals, such as the pig, rabbits, cats and dogs, the mammae are distributed in two mammary lines along the ventral surface. The number of the mamma? in such cases is notoriously variable, and in some respects this variation is interesting and has a bearing on questions of the nature of Meristic Repetition. If a number of such animals be examined it will be found that as a rule there are the same number of glands on the two sides, and that they are arranged in pairs, those of each pair standing at the same level or nearly so. Nevertheless departures from this arrangement are very frequent. Individuals are in the first place commonly found with a different number of mammae on the two sides, and in such cases it is interesting to observe that together with the difference in the number of mammje on the two sides

FIG. 33. Diagram of nipples in a male Bull-dog. On right side, four ; on left, five ; the two anterior and two posterior being almost at the same levels. •limb, umbilicus. The dotted line shews the outline of the thorax. rally if m-i alway- a disturbance in the paired arrange- !•;:{. im-ii!. A -impl.- «-a-- oi this kiud occurring in the dog is represented in I 33 Tli.- animal i> a male bulldog lately in my possession. <>n th«- i le there are four nipples, while on the left there

ti\i-. Tinmost anterior «m each .side stand almost at the same Similarly the ni".-t posterior nipples stand on each side at alnn»t • tly tip -aim- I'-vel on the sheath of the penis, the total length from tin' first to the last nipple on each side being practically the same. ' 'n the left however there are two nipples placed between th'- second and tinla-t. but »n the right there is only one. This nipple stands at a level not far from the middle between the

:'>id and 4th of the <. ther side, making as it were a complement to I (''4. Thirty-five \i>iin^ pigs examined with regard in these questions Th- - were all quite \..un^. about a fortnight old, and conse- '|iientl\ there wano displacement due to functional development *'•"• i'. being Q« Further apart bhananj oftheothers. The measurements of the distances between the nipples on one side in one of these cases were, in inches,!^, 1, ^, TTT,J$> It'Trr* tne rudimentary nipple standing y^ in. from either of its neighbours. In the D

FIG. 34. Diagrams of nipples in very young pigs. Letters refer to groups in No. 104. group this was found on both sides, but in the E group on one side only, as in the figure (Fig. 34). On looking at a series of cases like those roughly illustrated in the diagrams, one is tempted to inquire as to the factors which determine the positions of these mammas and nipples. Though such an inquiry must lead to small definite results it may not be unprofitable to point out some deductions \vhich may be made from the facts. I take this opportunity as a good one for illustrating the position here adopted with respect to the theory of Reversion, and for discussing certain features of the phenomena of Division.

The mammary glands form an example of a class of Meristic organs which are distributed in series along a body already segmented, but whose positions have no obvious coincidence with the fundamental segmentation. In the case of the pig, for instance, it would doubtless be found that the mammae bear more or less definite relations to particular vertebras, but they are not limited to such positions as the ribs or spinal nerves must be. The segmentation of the mammas is thus a segmentation, or serial arrangement, superadded upon that of the vertebrae. The question to be considered is, what determines the points at which mammas are to be formed ?

In the paper to which reference has been made, WILLIAMS has contended for the view that each somite bore originally a pair of mammas ; and we may remark that if this were so the problem of the segmentation of the mammae would be the same as that of the -e,,eral -.--mentation of the trunk. The same author then argues 'that th" appearance of supernumerary nipples or mamma' along tli.- mammary lines is a reversion to an ancestral condition, and a . believed to have been placed, definite ordinal numbers being

raed to each. Against this suggestion may be urged those ob- LODS to appeals to the hypothesis of reversion which were men- 'tioned in th.- Introduction (Section XII.), but in addition to these there are a number of objections applying specially in the case of mammar) Variation. The view that supernumerary mamma' are rsions r>--ts on the frequency and deh'niteness with which they occupy certain positions. But 'though they do occur more often in -oiHe po-itionthan in others they are in no sense limited to the-,- position-, tor they may stand anywhere, at least upon the mammary lines. To justify the view that the positions of supernumerary mammae are definite it is necessary to exclude the cases ,,t hitid nipple, of multi])le nipples on the same breast, and of axillary i '\i. -n-ions of the mammie, all which phenomena would then he'look.-d "ii as belonging to a class different from that of actual supernumerary mammae. In the argument referred to, this course i- actually adopted. The acceptance of such a view leads to givat ditHculty.' Foiexample, in Neugebauer's case (see Fig. 2!)), Williamconsiderthat the posterior nipples of the two sides belon- to different pairs, and have consequently different homologies, use they -tand at different levels.

Sueh di-tincti<>n- are. 1 believe, unreal. It is surely impossible t<> suppo-e that the Repetition seen in the udders of the two cows in !•' I-: '.'•- i- a phenomenon different in the two cases. In the one there are two extra teats in symmetrical positions, equally spaced ..lit from the second teats; in the other there is a third teat on one -id.- and a double second or posterior teat on the other. Surely it j- dear that the double condition of this teat represents an im- p.-rfect pha-e ..f a process perfected on the other side. If further proof were needed it ma\ l>e found in the fact already mentioned, that th" mamma' of the pi;.; and other such animals, may be the -Hue in number .sen mi the two sides, but nevertheless stand quit" irregularly and without any \isih|e arrangement into pairs.

The existence of these cases in which no order of form or regularity can lie traced may seem at first sight' 1o lie an insuperable olijeciion to any attempt at the detection of principles in the arrangemenl »f the mamma'. There is howeyer the fact that many, and indeed in most forms the majority of individuals do shew an orderly and paired arrangement, and the further fact that of those cases which depart from this, a certain number present appearances \\hich suggest that t his depart ure has conic about in a regular \\-.\y. Though the irregular cases remain, something would be •j. lined if \\e could comprehend any of the elements on which the