46 THE BREEDING OF ANIMALS 



cells in this investigation was microscopic evidence of 

 normal motion and as pointed out by Lewis this method 

 does not necessarily measure the ability of the sperm 

 successfully to fertilize the ovum. The addition of water 

 to semen seems to lower the vitality of the sperm-cells. 

 The presence of urine also has a retarding influence on 

 the activity of the spermatozoa. Sperm-cells kept in 

 contact with rubber lose their vitality more quickly than 

 when preserved in a glass retainer. 



47. Vitality of spermatozoa within the female genera- 

 tive organs. How long do the sperm-cells retain their 

 vitality after being deposited in the generative organs 

 of the female ? The answer to this question is of practical 

 importance, as it has an important bearing upon the 

 particular time or stage during the heat at which the 

 union of the male and female will be most likely to result 

 in offspring. 



The period during which perfectly healthy sperm-cells 

 retain their vitality and power of motion under labora- 

 tory conditions is comparatively short. And while 

 the conditions for a longer period of vitality are pre- 

 sumably much more favorable inside the generative 

 system of the female, yet investigations on mares and 

 sows 1 seem to point to the fact that the life of the sperm- 

 cells in the uterus of the female is comparatively brief. 

 This is contrary to the opinion of many practical breed- 

 ers. It is generally believed that the spermatozoa retain 

 their vitality in the reproductive organs of the female 

 for a number of days. It is stated by some veterinary 

 authorities 2 that the spermatozoa will live in the vagina 

 or womb of the mare from six to twelve days under the 



1 Lewis, Oklahoma Experiment Station, Bulletin 96. 



2 Breeder's Gazette, vol. 43, 1903, p. 683. 



