122 COMPARATIVE PHYSIOLOGY OF THE BRAIN 



the stimulus of the operation. Abnormal positions 

 of the legs, resulting from the operation, occur just as 

 in Astacus and Squilla. 



If the supra- and subcesophageal ganglia be re- 

 moved by decapitating the animals, they are still able 

 to perform some walking movements, and especially 

 hopping movements, when stimulated. This agrees 

 with the idea of the preservation of the purely seg- 

 mental arrangement of the nerve-connections. Yer- 

 sin's experiments on crickets are very significant in 

 this regard. I take them from Bethe's paper. They 

 deal with crickets from which both longitudinal com- 

 missures had been removed between the subcesophag- 

 eal ganglion and the first thoracic ganglion. Yersin 

 kept these animals alive for weeks. " When laid on 

 their backs they were able to turn over. When stim- 

 ulated they moved forward a few steps, or to the side, 

 according to the point of stimulation. In doing so 

 they occasionally tumbled over. When stimulated, 

 they still made attempts at flying without being able 

 to lift themselves from the ground." Yersin observed 

 that a male and a female, both of which had been op- 

 erated upon in this way, were able to pair. Of course 

 it was necessary to place the male on the female in 

 this case. The male on which he made this observ- 

 ation had already given off a spermatophore. 



Bees lived only a short time after the extirpation 

 of the supracesophageal ganglion. The bee shows 

 the same restlessness that was noticed in Astacus. 



Bees whose brains were divided lengthwise in 



