DEVELOPMENTAL STIMULI IN THE CESTODA. 



129 



The cirrus (/, Fig. i) is eversible, working on the same prin- 

 cipal as a Nemertean proboscis, a type common in Cestodes. 

 From its base the much-coiled vas deferens (fd) leads away and 

 is found throughout these coils crowded with sperm. At its 

 inner end it has a denser wall and is of less diameter for a short 

 distance (i>d) and then divides into the vasa efferentia which can 

 be seen radiating to the area in which the testes are located and 

 in favorable cases followed down to the testicular follicles them- 

 selves (Fig. i). 



The vagina (W) which opens on the genital papilla just above 

 the penis will be seen in the figure to pass inward and curve 

 around backward, passing behind the mass of finger-like follicles 

 which constitutes the ovary (o). It is here enlarged into the 



SR 



YD 



SG 



FlG. 3. Ducts of female complex with ovary lobes left out and ducts reflected 

 slightly to show connections, cd, duct from ootype to inner end of vagina ; cyd, com- 

 mon yolk duct ; eJ, egg duct ; o, ovary ; of, ootype ; sg, shell gland ; sr, seminal 

 receptacle of vagina ; v, inner end of vagina ; x, meeting place of ova and yolk ; yd, 

 right and left yolk ducts. 



seminal receptacle which will be found full of sperms. Lying 

 among the posterior lobes of the ovary is the shell gland (sg) to 

 which the yolk is delivered from a common yolk duct formed by 

 the union of a single yolk duct (yd) coming from either side. 

 Extending anteriorly from the shell gland and beneath the ovary 



