THE ACCESSORY REPRODUCTIVE ORGANS 245 



supposed by Landwehr 1 to be due to the presence of fibrinogen, 

 twenty- seven per cent, of which was found to be present. Calcium, 

 however, could not be discovered. Camus and Gley ~ state the 

 clotting is brought about by a specific ferment (which they call 

 vesiculase) in the prostatic secretion (see p. 248). 



The clotting of the fluid, after its entrance into the female 

 passages in Rodents, prevents the escape of the spermatozoa and 

 so helps to ensure fertilisation. This fact was first discovered by 

 Lataste, 3 who speaks of the " bouchon vaginal" formed by the 

 solidified secretion of the vesiculae. Similar observations have been 

 made by Leuckart 4 and others. The " bouchon vaginal " is said to 

 remain in situ for several hours, and then to become softened and 

 fall out. 



The vesiculre of the hedgehog during the breeding season 

 contain a great quantity of yellowish-white fluid containing a 

 large number of irregularly shaped crystals resembling small ill- 

 formed crystals of edestin. Hopkins 5 has examined chemically 

 the centrifugal precipitate obtained from the vesicular fluid, and 

 found it to consist mainly of a peculiar phospho-protein which 

 differed from most other phospho-proteins in its resistance to 

 solution in alkalis. He regards its existence in such large quantity 

 in a physiological secretion as a remarkable and exceptional 

 phenomenon which must presumably have some peculiar signi- 

 ficance. It has not been described as present in the vesicular 

 fluid of other Mammals. 



Tarchanoff 6 has suggested that in the frog the filling of the 

 seminal vesicles serves to excite sexual feeling in the male during 

 the breeding season. He states that the injection of milk, by 

 causing distension, excited sexual desire. But certain other obser- 

 vations have been made which seeni to disprove Tarchanoff's 

 conclusions (or at any rate to show that they are 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 



1 Landwehr, " Ueber den Eiweisskorper (nbrinogene Substanz) der Vesicula 

 seminalis der Meerschweinchen," P finger's Archiv, vol. xxiii., 1880. 



a Camus and Gley, " Note sur quelques faits relatifs a 1'enzynie prostatique 

 (vesiculase) et sur la fonction des glandes vesiculaires," C. It. de Soc. d<> Kiu!., 

 vol. iv. (10th series), 1897. 



3 Lataste, "Sur le bouchon vaginal des Rongeurs," Zool. Am., vol. vi., 1883. 



4 Leuckart, Zur Morphologie mid Anatomie der (Jesehlec/itso/'ga/ie, Gottingen, 

 1847. 



" Hopkins, Addendum to Marshall's paper 1 , loc. ait. 



. 6 Tarchanoff, "Zur Physiologic des Geschlechtsapparates des Frosches," 

 Pfliiger's Arckiv, vol. xl., 1887. 



7 Steinach, " Untersuchungen zur Vergleichenden Physiologie der Mann- 

 lichen Geschlechtsorgane, etc.," Pftiiger's Arcfa'p, vol. Ivi., 1894. 



