REACTIONS OF PROBOSCIS OF PLANARIA 



97 



and the ventral nerve of that side of the body. There was no 

 evidence of reaction of the proboscis. Then the other margin 

 of the body with its ventral nerve was cut away, and, though 

 there was no damage done to the sheath or to the base as such, 

 the proboscis at once suffered autoamputation and swam about 

 ingesting food (B). 



F g. 10 A, cut made on right side of body too shallow to include lateral nerve- 

 trunk, proboscis inactive; B, cut on left side removing lateral nerve-trunk, pro- 

 boscis projected, but remained inactive; C, second cut made on right side remov- 

 ing other lateral nerve-trunk, proboscis active. 



5. Figure 10 shows an experiment that yields evidence of this 

 nervous inhibition. First a very narrow edge of the body was 

 cut away — too narrow to include the nerve-trunk. There was 

 no reaction of the proboscis. Then, from the other side a strip 

 was cut deep enough to take away the nerve-trunk of that side. 



THE JOURNAL, OF EXPERIMENTAL ZOOLOGY, VOL. 26, NO. 1 



