324 Gilman A. Drew 



that the response is quicker and more marked by way of the pedal 

 than by way of the visceral. Much the same results were obtained 

 by stimulating the tentacles on one side of the ventral mantle 

 opening after the cerebral commissure was cut, as were obtained 

 by stimulating one side of the collar. 



Other experiments were tried to determine to what extent 

 impulses can be made to travel over association fibers in other than 

 what w^ould seem to be the usual ways. It was found that stimu- 

 lating one ganglion of a pair readily affected to its fellow gan- 

 glion and that the disturbance could be readily passed on from 

 this ganglion to others provided the transfer was of a nature 

 that was probably usual. For example, if the right cerebro-vis- 

 ceral connective was cut and the right posterior pallial nerve was 

 stimulated, all of the organs connected directly with the visceral 

 ganglia on both sides responded, and, a little later, the organs con- 

 nected with both sides of the cerebral ganglia and the foot re- 

 sponded. If the left cerebro-pedal connective of the same speci- 

 men is also cut and the same stimulation is given, the response 

 of the foot is delayed slightly but not long. In the last case it 

 has been necessary to send impulses from the right to the left 

 visceral ganglion, from the left visceral ganglion to the left cere- 

 bral ganglion, from the left cerebral ganglion to the right cerebral 

 ganglion, and from this to the right pedal, which in turn must 

 stir the left pedal to action with it. It will be noticed that all 

 transfers in this experiment are in directions that may be sup- 

 posed to be usual, either from one ganglion to another of a pair, 

 or by way of warning from the visceral to the cerebral, or from the 

 cerebral to the foot. These impulses are sent so readily that in 

 one case it was found that by stroking the siphons of a specimen 

 that had been operated on in the manner described, regular 

 burrowing movements were instituted. Stimulation of the ten- 

 tacles on the left side of the ventral mantle opening gave results 

 almost as quickly as on uninjured specimens. Here again the 

 impulses from one ganglion to another are in usual directions. 



On other specimens, when the left cerebro-pedal connective 

 was cut and the left side of the collar was stimulated, the foot 

 responded without delay. Impulses were moving in usual direc- 



