234 THE PHYSIOLOGY OF REPRODUCTION 



" bouchon vaginal " is said to remain in situ for several hours, 

 and then to become softened and fall out. 



TarchanofE ^ bas suggested that in the frog the filUng of the 

 seminal vesicles serves to excite sexual feeling in the male 

 during the breeding season, but certain other observations 

 have been made which seem to disprove this (or at any rate 

 to show that it is not universally true). Thus, in some 

 animals, it is known that sexual desire exists before the 

 seminal vesicles become full. Moreover, Steinach ^ found 

 that rats, whose seminal vesicles had been removed, still 

 retained their desire for copulation although their fertility 

 was diminished. 



That the spermatozoa possess complete functional activity 

 before they can be in any way influenced' by the secretion of 

 seminal vesicles has been conclusively shown by Iwanoff,^ who 

 induced pregnancy artificially in rabbits, guinea-pigs, and other 

 animals, by injecting into the female passages fluid obtained 

 directly from the epididymis, and mixed with a 5 per cent, 

 solution of sodium carbonate. The diminished fertihty in 

 Steinach's rats, after the removal of the vesiculae, was probably 

 due to the absence of formation of the " bouchon vaginal," as 

 has been suggested by Rauther.* 



It would seem probable that, in the majority of animals 

 which possess vesiculse seminales, the secretion of these glands 

 serves to dilute the semen, and so assists in providing a fluid 

 medium for the transference of the spermatozoa. 



Exner^ has suggested that the seminal vesicles may have 

 the function of absorbing the seminal fluid which is not ejaculated, 

 but there is little evidence that this is the case. 



Lode * found that in castrated bulls, horses, and guinea-pigs, 

 the glandular epithelium of the vesicles atrophied, but the con- 



I Tarohanoff, " Zur Physiologie des Geschlechtsapparates des Frosches," 

 Pfiuger's Archiv, vol. xl., 1887. 



' Steinach, " TJntersuohungen zur Vergleichenden Physiologie der Mann- 

 lichen Geschleohtsorgane," &c., Pfiuger's Archiv, vol. Ivi., 1894. 



' Iwanoflf, " La Fonction des Vi^sicles seminales et la Glande prostatique," 

 Jour, de Phys. et de Path. Gen., vol. ii., 1900. 



■• Eauther, loc. cit. 



'> Exner, " Physiologie der Miinnlichen Gesohlechtsfunktionen," Frisch and 

 Zuckenhandl, Handbuch der Urologie, 1903. 



* Lode, loc. cit. 



