THE VAS DEFERENS. 697 



The thick layer of annular fibrils, which surrounds the coils of the 

 seminal duct, effects probably only the forward movement of the 

 internal seminal mass, forcing it into the cirrhus. 



That the cirrhus is really a copulatory organ is, in spite of Lan- 

 dois and Sommer's contradiction, all the more certain since the sensory 

 papilla? on the genital area point clearly to a sexual association of the 

 joints ; but this is still far from having been verified by observation. 



The Vas Defer ens is directly continuous with the canal within the 

 cirrhus-pouch, as has been described above, and the cirrhus-pouch 

 itself is a muscular apparatus developed round about it. One might 

 therefore readily suppose that the entrance of the vas deferens into 

 the pouch coincided with its distal pole, as its aperture does with the 

 proximal. Such is not, however, the case. The entrance of the vas 

 deferens occurs rather at the portion turned backwards, towards the 

 hinder border of the joint, and at a considerable distance from the end 

 of the cirrhus-pouch, so that the latter arches above it in the form of 

 a hemispherical protuberance, while the spirally coiled canal within 

 forms in its windings an arch open posteriorly. It is of course only 

 the quiescent state of the cirrhus-pouch which exhibits this appear- 

 ance, for with the protrusion of the cirrhus the caeca! ly projecting 

 portion of the pouch undergoes a reduction, in consequence of which 

 the insertion of the vas deferens becomes apparently altered. 



Just at its point of entrance into the cirrhus-pouch the vas 

 deferens is further surrounded by an ovoid bulb, which, though of 

 course much inferior in size, rarely measuring mor6 than 0*2 mm. 

 long by 0*4 mm. thick, undeniably recalls the structure of the cirrhus- 

 pouch by its muscular character, and by the coiled course of. the canal 

 within it. There are indeed many differences in detail. Not only is 

 the connective tissue much less developed in proportion to the mus- 

 cular tissue, but the latter seems to be somewhat differently disposed, 

 since the radial muscles are absent, and the others are united in a 

 close web, whose fibres extend for the most part annularly, partly, 

 however, crossing one another diagonally. Longitudinal fibres are 

 only present in small numbers. 1 It can hardly be doubted that this 

 muscular bulb serves to force into the cirrhus-pouch the semen which 

 frequently collects in considerable quantity within the canal. 2 Ac- 

 cording to Botticher, it simply represents a seminal vesicle. 



The vas deferens is seen as a highly coiled canal, extending on 



1 I could not seethe strong cilia which Moniez (loc. cit., p. 144) found within the 

 bulb, and which had a distinctly cellular character ("les cils sont volumineux, leur 

 nature cellulaire ne peut (Hre mise en doute "). Nor could I perceive the cilia in the 

 vagina which he has described (ibid., p. 148). 



2 Eschricht overlooked this apparatus, for the citation by Stieda and others to the 



