VARIOUS FORMS OF TAPEWORMS. 



59 



contain a vesicle. Development proceeds very slowly. l!y 

 the end of five months, Leuckart has shown that they attain 

 the size of a walnut. They now consist of a whitish-yellow 

 vesicle with thick walls composed of two layers (fig. 17) 

 — the outer one thick, and called the hydatid membrane 

 (ft) ; the inner one thin (???), and known as the germinal 

 membrane. Internally this " mother - vesicle " contains a 



._vp£^ 



Fig. 17. — Diauram .showing formation of Pboligerous and Secondary 

 Vesicles in Echinococcus. Railliet. 



ct, Hydatid membrane ; m, germinal vesicle ; vp, proligerous vesicles ; vf, daugliter- 

 vesiclc commencing to form ; vf, daughter-vesicle passing externally ; vf, daughter- 

 vesicle passing internally ; vfi, internal daughter - vesicle ; vfe, external daughter- 

 vesicle ; vpji, internal grand-daughter- vesicle ; vpfe, external graud-daughter-vesicle. 

 (From Par, Dis. Ani., Neumann.) 



colourless neutral fluid. In some cases the " mother- vesicle " 

 remains in this state, no scolioes being produced, when it 

 is called an " acephalocyst." Should further development 

 take place, as is usually the case, a number of buds, close 

 together, arise from the germinal layer (vp). These buds 

 become hollow, and from their internal walls soolioes appear. 

 As many as thirty scolices may be formed in each of these 



