192 



UNSEGMENTED "WORMS" 



solved, and embryos (hexacanths) bearing six anterior 

 hooks are liberated. They bore their way from the in- 

 testine into the muscles or other structures, and there 

 encyst. They lose their hooks, increase in size, and 



FIG. 99. Diagram of reproductive organs in Cestode joint. 

 Constructed from Leuckart. 



., Ovary, with short oviduct; ut., "uterus"; /., diffuse testes; 

 .y^.^-., shell gland ; y.g.,yp\k gland ; z\*.,vas deferens ; z/., vagina ; 

 r.s.j receptaculum seminis; I.e., longitudinal excretory ducts; 

 i.e.) transverse bridges connecting these. 



The dotted lines above and below represent the anterior and 

 posterior borders of the proglottis. Note that the so-called uterus 

 is blind ; it opens to the exterior in a few tape-worms, and is 

 perhaps the homologue of the La urer-Stieda canal of Trematocles. 



become passive, vegetative, asexual "bladder-worms." A 

 bud from the wall of the bladder or proscolex grows into 

 the cavity of the same, and forms the future " head " or 

 scoleoc This is afterwards everted, and then the bladder- 



