46 VARIATION 



One of the most remarkable cases ever described is that of 

 an infant brought to Guy's hospital in iSsi. 1 Ano'ther was 

 of a child having a well-developed supernumerary auricle on 

 each side of the neck (see Fig. 6). These appendages were 

 easily removed and proved to be entirely cutaneous, though 

 each was served by a small artery. 



Whether cervical fistulae are to be regarded as remains of 

 unclosed gill slits, or whether they are to be regarded as repeti- 

 tions of the external ear, in any event their presence shows a 

 pronounced tendency to repeat certain characteristic structures 

 in this particular region of the body. 



Growths of this character are by no means confined to man. 

 Cervical auricles (the so-called " wattles ") are common in sheep, 

 especially merinos. They are well known in goats and are ex- 

 ceedingly common in many strains of unimproved swine. Strange 

 as it may seem, these repetitions of the ear appendages are un- 

 known in either the horse or the ox. 



Meristic repetition in mammae. 2 One of the chief distinguish- 

 ing features of mammals is milk secretion. Speaking generally, 

 this occurs at some point or points on either side of the ventral 

 surface of the body on lines running from the armpit to the 

 groin. In swine and in dogs it is distributed throughout the 

 entire extent of these mammary lines. In cattle, horses, goats, 

 sheep, etc., it is confined to the rear extremity of the line, and 

 in the elephant it is as decidedly forward, the udder being located 

 at the armpit. In the human being the point of normal activity 

 is relatively further back (down) than in the elephant, but yet 

 above the middle. 



This latter point is established by the fact that supernumerary 

 nipples are found both above and below the normal. The fact 

 that no less than three supernumeraries have been found above 

 indicates that the normal mammae are perhaps fourth in a full 

 series. It is to be noted in this connection, however, that in 

 most cases supernumeraries are situated below rather than above 

 the normal. These structures vary all the way from mere nipples 

 resembling warts and entirely unaccompanied by mammary tissue 



1 Bateson, Materials, etc., p. 178. 2 Ibid. pp. 181-195. 



