THE TAPEW0R:M LARV.E 



211 



germinal membrane when the mother vesicle has developed to a suffi- 

 cient size. At first papillary, each has a cavity that gradually enlarges, 

 and the vesicles thus formed have an attachment to the germinal mem- 

 brane by a short pedicle. Within each there develops a variable num- 

 ber — usuallv five to twentv or moi-e — of little oval bodies. These are 



Fig. 117. — Diagram of EchiuDcocus liydatid: cu, thick cuticu- 

 lar monibrane; gr, germinal ni("iiil)raiic; a. b., development of 

 proligerous vesicle; c, development of the heads according to 

 Leuckart; d, development of heads according to Moniez; e, fully 

 developed brood capsule with heads; f, brood capsule has ruptured 

 and the heads hang into the lumen of the hydatid; g, liberated 

 head floating in the hydatid; h, i, k, 1, m, formation of secondary 

 exogenous daughter cyst; n, o, p, formation of endogenous cyst, 

 after Kuhn and Davaine; cj, daughter cyst with one endogenous 

 and one exogenous grand-daughter cyst; r. s., formation of en- 

 dogenous daughter cysts, after Xaunyn and Leuckart; r, at ex- 

 pense of head; s, from brood capsule; t, constricted portion of the 

 mother cyst (copied from Osborn's "Economic Zoology," after 

 R. Blanchard; Bureau An. Ind., U. S. Dept. Agr.) 



the lar\'al tapeworm heads. When completely formed the heads meas- 

 ure slightly more than 0.1 mm. and show the suckers and double crown 

 of hooks. 



5. Daughter or secondary vesicles sunilar in character to the mother 

 vesicle have origin in the hydatic membrane which they distend and 

 finally rupture, faUing into or outside of the mother vesicle. In the 

 first case they are termed endogenous vesicles., in the second exogenous 



