PLATE XIV. 



Fig. 21. — Section of an ovicell of C. ebumea containing an embryo in the 

 three-cell st:icv. The outer layer of cells represents the ten- 

 tacle sheath (tail.), and the cavity between it and the follicle 

 (fl.) is the cavity of the tentacle sheath (tent. car.). ■ 600 



Fig. 22.— Another four-cell stage of <'. chitmcii, in which the blastomeres 

 are separated (bl.) and between them are numerous small cells 

 (sm. ft. els.). The spherical follicle (fl. els.) is diminished, the 

 tentacle sheath is well developed (tent.), and below the embryo 

 in the proximal portion of the ovicell are numbers of mesen- 

 chymatous cells (mes. tin.). ■ 600 



Fig. 23. — Section of an ovicell showing tour blastomeres of an embryo in 



the eight-cell stage. The i centric layers of follicle have 



decreased (fl, els.), while the small cells (sm. ft. els.) inter- 

 polated between the blastomeres have greatly increased. Coo 



Fig. 24. — Section of an ovicell containing an embryo whose blastomeres 

 have united to form a ball (emb.) which is still surrounded by 

 the follicle (ft. els.). Close to the embryo are a number of 

 the small follicle cells (sm.fl. els.). 600 



Fig. 25.— An advanced stage in ovicell and embryo formation. The follicle 

 cells have disappeared, and within the tentacle sheath above 

 and below the embryo are a number of cells of the mesenchyme 



(mes. lis.). ■ 600 



Pig. 20. — Section of a ball stage of Crisia occidentalis representing an 

 embryo at about the same stage of advancement as that in the 

 preceding (Fig. 25). A portion of the original spherical follicle 

 yet remains (fl, els.). Below the embryo is the chitinous 

 septum (chi. r.). separating the ovicell into two parts. The 

 chitinous tube (chi. t.) contains large numbers of cells forming 

 a network. Among them are numbers of multinucleaied or 

 giant cells (gi. els.). 600 



Fig. 27. — Section of an ovicell of C. ebumea, containing a budding embryo 

 (prim, emb.), and a number of secondary embryos (see. emb.). 

 At various points on the surface of the primary embryo are a 

 number of projections, indicating the formation of buds (in. bd.) 

 or secondary embryos. The follicle is represented by a number 

 of scattered cells (ft. els. ) . The tentacle sheath is intact ( tent. ) . 

 300 



