30 



SOURCES OF KINETIC AND METABOLIC HORMONES 



Ephemeroptera (Arvy and Gabe, 1953) and Plecoptera, where 

 their axons are connected anatomically to the ventral gland 

 (Fig. 2-8). Experiments have shown that in higher insects the 

 suboesophageal ganglion is the source of a kinetic chromactivating 



HEAD 



Ocelli 



PRO- 



PROTHOR 



An.ii 



DEU' 



Fr. gang 



— Aorta 



Mouth 



Lbr Mdb Mx i Mx ii Vent, gl 



Leg I 



Fig. 2-8. Central nervous system and sources of hormones in the 

 head and prothorax of a hemimetabolous insect, in lateral view. 

 The nervous system, with optic lobes (OP) cut off, resembles that 

 of the crab (Fig. 2-5) and is similarly lettered and named, except 

 that Mx ii is here the labium, and ganglia of the ventral chain are 



