Basal Ganglia of Insects 117 



after a hundred trials, learned without a fault to 

 follow the right path by which to obtain its food 

 in a simple labyrinth. 



Professor Flourens found that after he had 

 removed the cerebral hemispheres of a frog the 

 animal continued to swim when thrown into the 

 water. Movements of this kind are due to 

 stimuli received by the tactile sensory organs 

 of the animal's body, which pass to the nerve 

 cells of the spinal cord and through their motor 

 fibres to the muscles concerned in the act of 

 swimming. The neuro-muscular system of 

 these animals has acquired the power of 

 executing these movements in virtue of the 

 hereditary structural arrangement of its ele- 

 ments, which had been exercised and thus im- 

 proved during the previous lifetime of the 

 animal. But, as Professors Goltz and Schrader 

 have shown, if, together with the cerebral hemi- 

 spheres, the basal ganglia are destroyed, the 

 animal loses all power of instinctive reflex 

 action; a frog thus mutilated will, if left to 

 itself, remain motionless until in the course of 

 time it dies. If the cerebrum of a frog is 

 removed exclusive of its basal ganglia, instinc- 



