650 THE PHYSIOLOGY OF REPRODUCTION 



and then successfully inseminate, it would be a very great economic 

 advantage to the breeding industry. 



That the spermatozoa of the bull may survive for as long as 

 twelve days within the removed testicle if the latter be kept at a 

 temperature a little above freezing point, has been shown by Iwanoft. 

 Outside the tissues of the animal Iwanoff found that spermatozoa 

 may preserve their motility for some hours in solutions of sodium 

 chloride, barium chloride, and potassium nitrate, but the exact lengths 

 of time do not appear to be stated, neither is the temperature 

 recorded. Ochi l and Sato '- confirmed these results and found further 

 that the artificial medium was improved if an isotonic solution of 

 glucose was added. They state also that oxygen in moderate amounts 

 is helpful in preserving the life of the spermatozoa. Yamane 3 gives 

 an account of successful experiments with injecting horse's semen 

 diluted with physiological salt solution and glucose, but the semen 

 was used immediately after dilution and not kept in the artificial 

 medium. Wolf, 4 working with rabbits' semen, found that for main- 

 taining the vitality of the spermatozoa two conditions were necessary ; 

 first, the reaction of the fluid should be as near that of normal blood 

 as possible ; and secondly, a sufficiency of " buffer salts " should be 

 present in order to prevent any great change in reaction due to 

 metabolism of the spermatozoa themselves. Wolf's general con- 

 clusion is that with " the combination of a properly balanced physio- 

 logical saline solution with an isotonic glucose solution, a sufficiency 

 of oxygen and a careful regulation of the hydrogen-ion concentration, 

 it is quite possible to keep these cells in a condition in which 

 motility can be restored on raising to body temperature, provided 

 that in the interval they are kept at a temperature near C." In 

 such an environment the spermatozoa could retain their potential 

 motility for nine days. 



ABORTION 



Abortion is often an important factor in determining a low 

 fertility, but its frequency of occurrenct' shows a considerable range 

 of variation. 



With women the frequency of abortion to birth at full term is 



1 < ><-hi, " Physiological Studies on Spermatozoa, especially its Life Duration," 

 .\<-t<i- M,,,/,,' .I/,-,/., Univ. Imp. in Kioto, vol. i., 1 !)!;. 



2 Sato, "On the Life Duration of the Horse Spermatozoa outside of the 



I: "h. I A/ .s 1 , /,/,/ .I/,../., I'niv. Imp. in Kioto, vol. i., 1916. 



Vanillin-. "Studien iiber die Physikalische und Chemische Beschaffenheit 

 des Pferdespermas, etc.," Jour, of CM. Agrie,, Hokkaido Imp. I'niv., vol. ix., 

 1921. 



4 Wolf, "The Survival of Motility in Mammalian Spermatozoa," Jm: <>f 

 Agn>: >',.,/. vol. xi., 19i'l. 



