The Generative Orgaiis ii 



In a second group of cases, excessive volume of the fetus, 

 pelvimitr}- fails the veterinarian as he can not recognize, even if 

 called to do so, this over size, until he is brought face to face 

 with the consequent dystocia, and that fact alone demonstrates 

 the disparity in size between the pelvic canal and the fetus, which 

 is to traverse it. Nor does this occurrence, even when safely 

 overcome by the obstetrist, furnish any safe criterion for future 

 action except possibly suggesting a change of mating. Subse- 

 quent fetuses may be of normal size. 



It has moreover been asserted that sexual differences exist in the 

 pelves of domesticated animals, especially in the horse. This we 

 have been wholly unable to verify. It is claimed that the pelvis 

 of the mare is more ample than that of the stallion or gelding, 

 that its foramen ovale is larger, that the ischiatic notch is 

 broader and shallower, that the sacrum has less prominent articu- 

 lar ridges ; in other words, that the pelvis of the mare is specially 

 constructed as an organ of reproduction in a manner to facilitate 

 the passage of the fetus at the time of parturition. We have 

 critically examined a number of equine pelves and find among 

 them those of stallions or geldings fulfilling the description given 

 as tj'pical of the mare in every regard and, vice versa, a mare 

 pelvis fully meeting all the alleged characters of the male. So 

 far as we have been able to determine, it is impossible to differen- 

 tiate the sex of any species of domestic mammals by the form or 

 size of the pelvis. 



B. The Generative Organs. 



The genital_systeiii of the mammalian female consists of the 

 ovaries , oviduc ts, uteru s, va^rina . vulva and mammae . Writers 

 variously divide them into internal and external, essential and 

 subsidiary, genital or copulatory ; each, however, is influenced by 

 the other and each is essential to normal reproduction. 



I. The Ovaries. 



In the protozoa, reproduction is effected by the division of a 

 single nucleated cell into two parts, alike in form and size, the 

 completion of the division establishing two individuals which 

 supplant the parent. 



Reproduction in the higher forms of animal life proceeds in a 

 somewhat similar manner from a single specialized cell, the ovum. 



