EXPERIMENTS ON ARTHROPODS 123 



symmetrical halves showed a perceptible functional 

 disorder only in their behaviour toward the hive. ' If 

 carried back to it they crawl about on the board be- 

 fore the entrance but make no attempt to enter, and 

 they pay no attention to their companions." 



If bees be decapitated, the supra- and subcesopha- 

 geal ganglion being thus removed, they are still able 

 to walk, although awkwardly. When laid on their 

 backs they turn over with the help of their legs. 

 " When stimulated on the ventral side they grasp the 

 object (pencil) with their legs, pull it toward them, 

 bend the abdomen, and attempt to sting it." But not 

 all animals give such favourable results. In brain- 

 physiology only those animals operated upon which 

 show the slightest disorders can be considered, be- 

 cause the exhaustion may render the rest of the cen- 

 tral nervous system pathological. 



As was to be expected a priori on the basis of the 

 segmental theory, the stinging-reflex is possible as long 

 as the abdominal ganglion is preserved. Bethe showed 

 that the abdomen, when severed from the body, still 

 bends if stimulated on the ventral side and reaches 

 the stimulated spot with the outstretched sting. At 

 the same time poison is ejected. The reflex also 

 continues when all the abdominal segments with the 

 exception of the last one have been amputated. 



If the supraoesophageal ganglion in a water-beetle 

 (Hydrophilus) be extirpated, the progressive loco- 

 motor movements are not only not interrupted, but tJic 

 animal goes about almost unceasingly, showing only 



