284 W. J. CROZIEE AND LESLIE B. AREY 



cal, although it is somewhat more quickly exhausted and only 

 rarely responds at all to shading. The responses disappear 

 under chloretone anaesthesia, but return again in sea-water. The 

 neuromuscular polarization of the gill plume is therefore a local 

 matter, conditioned by a self-contained nervous apparatus which 

 conducts impulses more easily distalward than proximally. 



These facts speak unmistakably for the presence of local 

 peripheral conducting paths, having the characteristics of true 

 nerve nets. Similar nerve nets have already been identified in 

 Octopus (Hofmann, '07), and in Aplysia (Bethe, '03). 



The body of Chromodoris may be laid open by a dorsal or a 

 ventral incision, and the animal will live for a long time in sea- 

 water. The nerves which originate from the ' cerebral' and sub- 

 oesophageal ganglia and traverse the body cavity are readily 

 employed for faradic stimulation experiments. The results of 

 such tests confirm Bethe's ('03) description of the effects of 

 nerve-trunk stimulation in Aplysia. Local responses, of no great 

 magnitude, are induced ; much more general effects are obtained, 

 with the same stimulus intensity, when the integument is acti- 

 vated directly. These experiments incidentally afforded infor- 

 mation relative to the old controversy as to whether the pro- 

 jecting marginal ridge is an epipodium (Herdman, '90; Herdman 

 and Clubb, '92) or a mantle structure proper (Pelseneer, '94, p. 

 70). Pelseneer was undoubtedly correct, at least so far as our 

 species is concerned, for the motor nerves to this region are 

 pallial, not pedal. 



3. The general result of these experiments is to suggest the 

 probability that peripherally a true nerve net is concerned in 

 local sensory responses, but that a reflex system involving cen- 

 tral conducting paths is called into play by more intense acti- 

 vation. We are able to offer in addition physiological proof of 

 a different kind that the peripheral conducting systems are nerve 

 nets, and that the central paths of nervous transmission are part 

 of a synaptic system, to which the term 'reflex' may properly be 

 applied. This proof is based upon the assumption that the 

 effect of strychnine affords a good test of synaptic transmission. 



