W. Ritchie 



189 



or tube arises known as the vas deferens {V.d.). The vasa deferentia unite 

 later to form a common duct {C.d.) which leads to the penis. The vas 

 deferens is much swollen but there are constrictions on it at two points. 

 The first constriction occurs at a point distant from the testis of about 

 one-quarter of its total length, while the second is at a point about a 

 corresponding distance from the other end of the vas. The first con- 

 striction is most marked, the second is not so conspicuous. The s^Vollen 



Fig. 11. Male reproductive organs of C. abietis (greatly magnified). On the right 

 the penis is shown in side view (more highly magnified). 



portion of the vas lying between the second constriction and its union 

 with the vas deferens from the other testis, i.e. the most posterior portion 

 of each vas, is called the seminal vesicle {S.v.). Two blind diverticula, 

 the accessory glands (A.g.), one on either side and placed opposite each 

 other, open into the vas deferens just at its second constriction. The 

 chitinous portion of the penis (P.) is composed of the fork (F.), ring 

 (R.) and sheath (*S'.). The fork gradually tapers to a point while anteriorly 

 Ann. Biol, v 13 



