34 



OBSTETIUCAL AXA TOMY. 



assume their maximum dimensions, which are maintained, with shght 

 variations, during the entire period of lactation. When this period is 

 terminated, the secretion gradually ceases, and the gland again assumes 

 its quiescent condition, and nearly its ordinary size.^ 



DlFFEEENCES IX OTHEK AxiMALS. 



Coic. 



In the Cow the mammae are also inguinal as in the Mare, and each 

 lateral mass, although enveloped in a single fibrous capsule, is made up 

 of two quite distinct glands— or " quarters," as they are commonly 

 termed — and which can be seen, or felt as limited by a slight depression. 

 Each gland has its corresponding teat, much more developed than that 

 of the Mare ; so that this animal really possesses four mammae and four 

 teats. The glands are compacted into a roundish mass, which is more 



Fig. 18. 



.Section or Uddek of Cow. 



a, Anterior Quarter ; h. Posterior Quarter ; g, Septum between the Quarters ; 

 c, c. Section of the Lactiferous Ducts ; (/, d. Lactiferous Sinus or Milk 

 Cistern ; e, e, Orifice of the Teat ; f, Large Lymph Gland in the Posterior 

 Quarter. 



or less pendulous when they are in active function ; in the centre of 

 each, and at the base of the teat, there is a single large galactophorous 

 sinus, which is the general confluent of all the lactiferous ducts, 

 and opens externally through the teat by a single excretory canal. 

 This canal is widest at its commencement, and narrow at its termina- 

 tion at the end of the teat. The walls of the latter are very thick, 

 elastic, and retractile. Not infrequently there are found behind the 

 foui teats one or two rudimentary teats, which are generally imperforate ; 

 though in very rare instances they have been observed to be perforate 

 and to yield milk. 



1 Li the male Horse we find rudimentary' teats, which are concealed within the 

 prominent annular fold of integument towards the extremity of the prepuce. They are 

 not i hvays present, however ; though they are so in the Ass, which has them largely 

 devel ped. 



