8. THE TENTACULAR APPARATUS WD EXTERNAL DIGESTION 



81 



ml- 



^ 



Fig, 54. I )evelopment of pinnules of Lamellisabella zachsi. Three successive stages {A, li and C) in 



longitudinal sections. 



cca - cell adjacent to capillary; <y> epidermis of tentacle; ////> basement membrane; ml longi- 

 tudinal muscle fibre; per peritoneum; />/', />r, pi' — successive stages of growth of the pinnules; 

 vp - capillaries of pinnules; vt - vessel of tentacle. (After Ivanov, 1960a.) 



Where they leave the base of the pinnule the capillaries turn in opposite 

 directions to run between the cells of the epidermis and communicate with 

 the corresponding tentacular vessels. Since the pinnules are usually arranged 

 in dense serried ranks, the intracellular parts of the capillaries present a 

 characteristic pattern in transverse sections (Figs. 53-55). 



