98 WILLIAM A. KEPNUR AND ARNOLD RICH 



The proboscis projected itself from the sheath, but hung there 

 perfectly quiet, showing no signs of activity. After several 

 minutes a second strip was cut more deeply from the side from 

 which the first narrow slice had been taken. This second cut 

 was deep enough to remove the nerve-trunk of that side, and the 

 proboscis at once underwent autoamputation and became active. 

 It is thus indicated that the severing of connection between the 

 proboscis and both lateral nerve-trunks is necessary, when the 

 sheath is intact, for the removal of inhibition sufficiently to 

 cause the proboscis to become hyperactive. 



The manner in which the basal ganglia have been removed in 

 our experimenting is rather crude. Needles, scalpels, and razors 

 were used in this work. It is quite possible that in these opera- 

 tions not only were the nerve connections destroyed, but pres- 

 sure in a varying degree must have been brought upon the 

 proboscis-sheath. This pressure as it varied might have dis- 

 turbed the thigmotactic conditions within the proboscis-sheath. 

 This latter contingency may account for certain variations in 

 the reaction of the proboscis as observed by us. For example, 

 two of three animals that had been severed but once, and that 

 near the bases of their proboscides, underwent autoamputation of 

 their proboscides and had their prehensile organs leave their 

 sheaths. The proboscis of the third specimen wriggled actively 

 within its sheath, but only swam out of the sheath when a hole 

 was made in the sheath with a needle. In addition to this 

 variation of reaction on the part of the proboscis, each of us 

 has had cases in which, after the ganglia adjacent to the base 

 of the proboscis had been removed, no autoamputation resulted. 

 More experunentation is needed to determine the cause of this 

 variation. At present we can only suggest that in cases like 

 these last ones we had caused no disturbance of thigmotactic 

 conditions in the sheath when we were removing the ganglia, 

 hence the proboscis was not excited and showed no response, 

 though the inhibition of the nervous system had been destroyed. 



It is indicated by the above experiments that the removal of 

 the ganglia posterior to the base of the proboscis does not ma- 

 terially disturb the control of the organ. The amputation of 



