THE ACCESSORY REPRODUCTIVE ORGANS 243 



I'he Vesicul^ Seminales 



The seminal vesicles are offshoots from the lower ends of the vasa 

 deferentia. They consist in man of coiled tubes, about five inches 

 long, into which several diverticula sometimes open. The structure 

 of the vesicles is similar to that of the sacculated part of the vas 

 deferens, but the muscular layers are relatively thinner. 



There has been some dispute as to the chief function of the 

 seminal vesicles. According to one view, they serve mainly as 

 receptacles for the spermatozoa before ejaculation. Most authorities, 

 however, are disposed to lay greatest stress upon their secretory 

 function. 



Rehfisch ^ has shown that if fluids are injected into the testicular 

 end of the vas deferens, they first enter the seminal vesicle and 

 afterwards pass out through the urethra. He concludes that the 

 vesiculse serve the double purpose of secretory glands and reservoirs 

 for the semen.^ Misuraca^ states that in dogs and cats, which have 

 no seminal vesicles,* the spermatozoa disappear from the male 

 passages from five to seven days after castration, whereas in guinea- 

 pigs, in which the vesicles are well developed, sperms may be found 

 ahve as long as twenty days after the removal of the testes. This 

 is regarded as evidence that the seminal vesicles function as recep- 

 tacles for the spermatozoa. Moreover, Meckel ^ stated that he found 

 sperms in the vesiculse of the mole in, the month of February {i.e. 

 during the breeding season) ; and Seubert ^ recorded a similar 

 observation about the hedgehog in August (also in the breeding 

 season) (cf. p. 55). Disselhorst,'' however, throws some doubt on 

 these observations. The present writer ^ has examined the contents 

 of the vesiculse of the hedgehog at all seasons of the year and has 

 failed to find spermatozoa even after the most careful search and 

 during the middle of the breeding season. 



' Rehfisch, "Neuere Untersuchungen iiber die Physiologie der Samenblasen," 

 Deutsche med. Wochenschr., vol. xxii., 1896. 



2 It has been pointed out that the passage of spermatozoa into the vesiculae 

 probably only occurs during the asphyxia of death in consequence of the 

 constriction of the vas deferens which forces the contained fluid into these 

 organs (Luciani, Hunmn Physiology, English Edition, vol. v., London, 1921). 



^ Misuraca, "Sopra un importante questione relativa alia castrazione," 

 Rivista sperimentale di Freniatria, vol. xv., 1890. 



'' Seminal vesicles are absent not only in dogs and cats, but in many other 

 CarnivOra, and also in Cetacea and Ruminantia. They are also wanting in 

 rabbits, but are present in the vast majority of Rodentia (Owen, Comparative 

 Anatomy, vol. iii., London, 1868). 



° Meckel, Beitvage zur Vergleichende Anatomie : 1. Ueher die Md/nnlichen 

 Geschlechtsteile des Maulwwfs, 1809. 



^ Seubert, "Symbolum ad Erinacei europsei anatomen,'' Inaug. Dissert., 

 Bonn, 1841. 



' Disselhorst, loc. cit. 



* Marshall, " The Male Generative Cycle in the Hedgehog," Jour, of Physiol., 

 vol. xliii., 1911. 



