26 



SOURCES OF KINETIC AND METABOLIC HORMONES 



in the brain still in place; removal of the sinus gland only (by 

 means of a minute punch, like an apple corer; Kleinholz, 1947) 

 leaves both sources undamaged and able to continue their 

 secretion. 



Dorsa 



SP HSPO ON SN 



X-SP 



Fig. 2-6. Eyestalk of prawn, Lysmata, cut open in the vertical 

 plane (cf. Fig. 2-5). Some neurosecretory cells in the ganglionic- 

 X-organ (GXO) in the terminal medulla (MT) have axons which 

 pass in a bundle (X-SG) to the sinus gland (SO) on the dorsal 

 surface of the external medulla (ME) ; others have axons (X-SP) 

 that pass ventrally to hanstrom's sensory pore organ (HSPO) 

 and end in "onion bodies" (ON), Both sinus gland and sensory 

 pore organ also have axons (B-SG and B-SP respectively) from 

 neurosecretory cells in the brain. The sensory pore retains some 

 sense cells (SP) connected by a sensory nerve (SN) to the brain 

 (from Carlisle, 1953). 



In the Malacostraca with long eyestalks, the sinus gland is 

 usually on the dorsal surface of the optic ganglion, either on the 

 internal or external medulla (Figs. 2-Sb and 2-6). It is largely com- 

 posed of an aggregate of swollen ends of the long neurosecretory 

 cell axons from the brain and the ganglionic-X-organ ; they con- 



