MAMMARY GLANDS IN BIMANA. 733 



they also are opposed to the papilla? of the lips of the child : being 

 highly vascular and nervous, they yield, when so grasped, a sen- 

 sation which is followed by erection of the nipple through a 

 fitting arrangement of its vascular tissue. The homotypal gland, 

 in the male, varies from four lines to two inches in diameter. 

 Astley Cooper succeeded 

 in demonstrating its conform- 

 able structure to the func- 

 tional gland in the female : 

 fig. 613 is taken from his 

 preparation. Under special 

 circumstances and stimuli 



SUCh £>"land may be developed Secerning follicles and ducts of the male mammary 



~ , gland, injected with quicksilver ; nat. size, cclxxxiv". 



so as to anord sustenance to 



the infant, of which more than one case has been recorded. 



The chief varieties in the female mammary organs relate to 

 prolonged periods of lactation, as in those inferior races in whom 

 the dugs become so extended as to permit the nipple to be thrown 

 over the shoulder to the child carried on the mother's back. 

 Cuvier noted an unusual breadth of the mammary areola in the 

 < Hottentot Venus.' 1 



Anomalies of supernumerary nipples and glands are rare. 2 



On a retrospect of the comparative anatomy of the mammary 

 organs we see that the modifications of these persistent tributaries 

 to the growth of the young mammal serve as little to charac- 

 terise groups as do the deciduous nutritive organs at the uterine 

 period of life. A pair of pectoral mammae would associate to- 

 gether as heterogeneous an assemblage of species as does the dif- 

 fused, or even the discoid, placenta. We may, however, discern 

 in part, the uses of mammary modifications ; whilst the teleological 

 relations of a zonular, a cotyloid, or a cotyledonal afterbirth can, 

 at best, be but very vaguely guessed at. 



§ 421. Adipose suhstances. — These are common to all orga- 

 nisms, protozoa, plants, animals. 3 In Mammalia they exist 



1 cclxxxv". 



2 In the instance narrated in cclxxxvi". the second nipple on each side was one- 

 sixth the size of the normal one, and situated near the anterior margin of the axilla. 

 When gently pressed, a milky fluid flowed from several ducts opening upon its 

 extremity. When milk was drawn from the normal breasts, a small quantity usually 

 escaped from the superadded nipples, but their flatness prevented the mother suckling 

 her children by them. 



3 Hunter, who sometimes clothed his far-reaching thoughts in paradoxical language, 

 writes : — ' Fat is no part of an animal : for first, it is not animal substance ; secondly, 

 an animal is the same without it as with it, — it is to be considered as an adventitious 

 matter; and thirdly, it is found both in vegetables and minerals, and, therefore, is a 



