314 KANSAS UNIVERSITY SCIENCE BULLETIN. 



the seat for coordinate movements. Bethe, however, does not 

 regard the subcesophageal ganglion as the centre for coordinate 

 action, since most of the arthropods that he operated on showed 

 few or no disturbances in coordinate movements after its re- 

 moval. In the grasshopper, as we have seen, the subcesoph- 

 ageal ganglion is not the chief centre for coordinate movements. 

 The destruction of the ganglion is followed by a severe shock 

 effect because it is accompanied by a great loss of blood and 

 necessitates a wound in a sensitive area. The insect can still 

 hop, fly, walk, and right itself, but in an awkward manner, and 

 shortly after the operation it seems to have lost its sense of 

 equilibrium. From the fact, however, that decapitation of the 

 grasshopper does not, as shall shortly be pointed out, destroy 

 coordinate progressive activities, it is evident that the ganglion 

 in the grasshopper does not preside over coordination of these 

 movements, though it may exert some influence over the sense 

 of the position of the body in space. 



IV. Decapitation. 



The supra and subcesophageal ganglia are removed by cut- 

 ting off the head. Usually a ligature is tied around the neck 

 before the head is cut off to prevent loss of blood. As was to 

 be expected from the foregoing experiments, the respiration was 

 not materially altered by the operation. It was only decreased 

 in rate. The lack of coordination in the rate of the thoracic 

 and abdominal spiracle movements, however, which may be 

 observed, is not due to any operative disturbance, since, as was 

 said before, this irregularity exists in normal insects. 



If a narrow strip of chiten is removed from the side of the 

 abdomen in a decapitated hopper, it is seen that the air-sacs 

 inflate in the inspiratory phase, and that, when the animal 

 struggles, the spiracle movements increase in frequency with 

 the movements of the abdomen and inflation of the air-sacs. 



Twenty-four hours after being decapitated, the animal hops 

 and flies four or more feet if it is touched. This depends upon 

 the species ; some normally fly further than others. 



When it is placed on its back it struggles and turns over, but 

 not so promptly as does the normal one. If, however, it is 

 carefully placed either on its side or back, it will remain so, 

 and, if its feet hold on to a stick, it will not attempt to right 

 itself from any position in which it is placed by changing the 



