BRAIN PHYSIOLOGY OF WORMS 359 



experiments had led me to suspect that this "spontaneous" 

 or "instinctive" burial was only a reflex called forth through 

 the stimulus of contact with sand. I tried whether it would 

 not be possible under certain conditions to demonstrate the 

 same reflex, even in brainless pieces. I laid such a brainless 

 piece upon the sand; as usual it remained quiet. I now 

 carefully covered the anterior end of this piece with sand. 

 The rest of the animal soon began to execute the typical 

 movements which are necessary to bring about the burial of 

 the animal in the sand. At the same time the glands at the 

 foot end of the animal began to secrete the sticky substance 

 which cements together the grains of sand and renders solid 

 the wall of the tube in which the animal lives. This secre- 

 tion is a constant accompaniment of the burrowing of the 

 animal. It is the same secretion which in other worms leads to 

 the formation of a tube. The animal did not however succeed 

 in burying itself, and so it soon began its movements anew. 



Spontaneous progressive movements were executed only 

 by that piece which contained the brain. Yet weak stimuli, 

 such as the shaking of the aquarium in passing through the 

 room, sufficed to bring about progressive movements in the 

 posterior piece. None of the pieces would remain on their 

 backs when turned over. When I attempted to keep a 

 brainless piece forcibly in this position it made great attempts 

 to return to the ventral position. In all the experiments 

 which have been described the size of the piece is not imma- 

 terial: the more segments it contains the more definite are 

 its reactions. I tried finally to determine whether all the 

 ganglia even the most posterior are able to bring about the 

 same winding and bending which is characteristic of the 

 injured worm. That is indeed the case. 



VI. EXPERIMENTS ON LUMBRICUS FCETIDUS 



I wished to determine whether angleworms are heliotropic 

 or photokinetic, and whether the decapitated animals show 



