232 Journal of Comparative Neurology. 



glion gives off from its dorsal ramus another nerve which runs 

 parallel to the posterior dissepiment and gives off branches to it. 



According to my reconstructions the fourth segment is a 

 typical one. In the third segment the middle and posterior 

 nerve leave the cord as a single nerve but soon divide into the 

 typical middle and posterior nerves. In the second segment the 

 same thing is found as in the third segment, although the mid- 

 dle and posterior nerves travel a much longer distance as a sin- 

 gle nerve, before they break up into the the typical nerves in 

 the second segment. In the first segment, two of the nerves 

 take their origin from the sub-oesophageal ganglion, and one 

 from the commissure; these nerves passing into the first segment 

 form an anastomosis between the circular and longitudinal mus- 

 cles very similar to the condition found in the other segments. 



The prostomium is innervated by a large double nerve from 

 each side of the brain. These nerves divide into numerous 

 branches as they approach the anterior end of the prostomium. 



From either side of the commissure two nerves are given 

 off which form a network around the oesophagus and pharynx. 

 This is very similar to the arrangement which Dr. Bristol found 

 in Nephelis. 



A Comparative Study of the Functions of the Central 



Nervous System of Arthropods. A Brief Summary 



OF the Results, by Albrecht Bethe.^ 



Translated from the German 



By W. W. Norman. 



The brain (supraoesophageal ganglion) of the Arthropods 

 is to be regarded first as an inhibitory organ ; in addition to 

 this it exercises a tone upon the musculature of the whole 

 body. It is also of course a central organ for the parts 

 of the body innervated by it. It is not however the seat of co- 



1 PJliigcr^s Arc/tiv., Rd. 6S, p. 449. 



