HORMONAL CONTROL 



553 



of these secretory areas are shown in Figs. 722 to 725, which also indicate 

 the position of the sinus gland, a gland-like structure also lying upon the 

 eye-stalk which acts as a storage -release depot for the secretions of the 

 neuro-endocrine cells (compare Fig. 692). 



It is interesting from the historical point of view that the sinus gland was first 

 considered to be the secretory organ of these hormones since most of the physiological 



Figs. 722 to 72.5. — The Neuro-endocrine System of Crustaceans. 



Fig. 722. 



Fig. 723. 



Figs. 722 and 723. — Neuro -secretory cells in the eye-stalk of a Crustacean, 

 Fig. 722 dorsal, and Fig. 723 ventral view of the right eye-stalk of Camharus. 

 BST, nerve tract from the cerebral ganglion to the sinus gland ; E\, the x-organ; 



E2-5, clusters of neuro-secretory cells ; LG, lamina ganghonaris ; ME, medulla 



externa; iV//, medulla interna ; }l/ J", medulla terminalis ; PLC, optic lobe peduncle; 



SG, sinus gland ; SGT, tract of sinus gland ; XST, nerve tract from the x-organ 



to the sinus gland; 1, 2, 3, fibre tracts (Bliss and Welsh). 



Fig. 724. Fig. 72.5. 



Figs. 724 and 72.5. — Neuro-secretory cells in the cerebral ganglion of a 

 Crustacean. 



Fig. 724 dorsal, and Fig. 72.5 ventral view of the cerebral ganglion oi Camharus. 



B\-5, regions of neuro-secretory cells ; CC, circum-a?sophageal connective'; 

 PLO, optic lobe peduncle (Bliss and Welsh). 



