84 A FURTHER KNOWLEDGE OF THE CYSTIC CESTODES. 



Fig. 13. — Isolated hook of M. Didymogastris Zeiss. F., oc. 3, cam. luc. 

 (x 900). a. r., anterior root; i. r., internal root; /.p., free 

 part of hook. 



Figs. 14-19. —Development of Scolex of Synhothrium. 



Figs. 14-18 are longitudinal sections of the anterior ends of blastocysts of 

 different ages. Drawn with Zeiss. A., oc. 1, cam. luc. ; details with Zeiss. 

 D., oc. 4. 



Fig. 14. — Longitudinal section of youngest blastocyst observed, with 

 developing invagination cavity. 



Fig. 15. — Further stage in development of same. 



Fig. 16. — Longitudinal section of blastocyst, with the knob-shaped process 

 arising from bottom of invagination cavity. 



Fig. 17. — Longitudinal section of blastocyst, with developing scolex. prh., 

 proboscis with developing hooks. 



Fig. 18. — Longitudinal section of blastocyst, with fully -formed scolex in 

 invagination cavity, hr., bothridium ; pr., proboscis lying in 

 cavity of proboscis sheath ; jjr. b., proboscis bulb ; r. msc, 

 retractor muscle ; i. v., invagination cavity ; iv. i. v. , wall of 

 invagination cavity. 



Fig. 19. — Fully-formed scolex of Synhothrium, separated mechanically from 

 the blastocyst ( x about 30). 



