PHYLUM CHORDATA 



3i7 



this structure, consisting of the two ventral longitudinal folds with the 

 groove between them, the term endostyle is applied. The cells covering 



br.car 



■vLsc.br 



itlom, 



Fig. 199. — Ascidia, diagram of longitudinal section from the left-hand side, the test 

 and mantle removed, atr. cav, atrial cavity; atr. siph, atrial siphon; br. car, 

 branchio-cardiac vessel; card, vise, cardio-visceral vessel; gonad, gonoduct; 

 hi, heart; ^//.hypophysis; mant, mantle; n.gn, nerve-ganglion; ess. oesopha- 

 gus ; ov, ovary ; red, rectum; stig, stigmata ; Horn, stomach; tent, tentacles; 

 test, testis; tr. v, transverse vessel; vent, v, ventral vessel; vise, br, viscero- 

 branchial vessel. (After Herdman.) 



the endostyle are large cells of two "kinds — ciliated cells and gland cells, 

 — the former beset at their free ends with cilia, the action of which is 



00. 



