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 
Fic, 99.—Diagram of reproductive organs in Cestode joint. 
—Constructed from Leuckart. 
+, Ovary, with short oviduct; w¢., ‘‘uterus”; #., diffuse testes; 
sh.g. shell gland ; y.g.,yolk gland ; v.d.,vas deferens; v., vagina 5 
7S., receptaculum seminis; Ze., longitudinal excretory ducts ; 
z.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 Laurer-Stieda canal of Trematodes. 
become passive, vegetative, asexual “bladder-worms.” A 
bud from the wall of the bladder or froscolex grows into 
the cavity of the same, and forms the future “head” or 
scolex. This is afterwards everted, and then the bladder- 
