INSECTA 



449 



for its autonomous action on the higher centres. For example a de- 

 capitated wasp can still walk and if a limb be removed from one side, 

 compensating movements of the remaining five legs enable the animal 

 to walk in a straight line. But the working together of the functional 

 units concerned, into different reactions, is controlled by the brain, 



ocn. 



Fig. 314. Nervous system of a grasshopper. After Uvarov. A, Ventral 

 chain. B, Brain and associated nerves. C, Optical section through head. 

 Mtrn. antennary nerve and ganglion; dc. deutocerebrum ; ocn. ocellar nerve; 

 op.ga. optic ganglion; pc. protocerebrum ; sug. suboesophageal ganglion; 

 syg. sympathetic ganglia ; tc. tritocerebrum. 



and the inhibitory character of that control is shown when the ganglia 

 are removed. A "decerebrate" bee will try to fly, walk, feed and 

 polish its abdomen all at the same ^ime. This is because no inhibi- 

 tion is being exercised on the functional units, which themselves 

 remain intact in spite of the removal of the higher centres. 



Sense organs. There can be no doubt that insects perceive stimuli 

 similar to those causing sensations in ourselves. They are sensitive 



