Fling, Netvoiis System of the Earthworm. 231 



ing the ventral cord, pass in a lateral and ventral direction 

 through the longitudinal muscle, and each nerve divides into 

 two branch"es or rami, one passing ventrally and the other dor- 

 sally between the layers of longitudinal and circular muscles. 

 From these rami smaller nerves are given off to the basement 

 membrane and finally these fibers reach sense organs at the 

 surface. 



Miss Langdon concluded that the dorsal and ventral rami 

 of these three nerves were not continuous over the mid-dorsal 

 and mid-ventral line. Dr. Hesse was not sure, but was rather 

 inclined to think that they did not cross the mid-dorsal and 

 mid-ventral line. 



The gold chloride method has been the most helpful to me 

 in my reconstruction. I have been able by this method to make 

 out the following points which I shall publish later in detail 

 with my plates. 



The two nerves mentioned above which leave the ganglion 

 in each segment, anastomose shortly after leaving it, and from 

 the posterior of the two nerves, at the place of anastomosis, a 

 nerve is given off to the dissepiment and walls of the intes- 

 tine. The nerve has been called the "sympathetic." 



The anterior of the two nerves passing from the ganglion 

 or the middle nerve of the segment sends its dorsal ramus close 

 behind the ventral and dorsal pair of setje and fine branches 

 are given off to each pair of setae. 



In all the forms I have examined I find that the dorsal and 

 ventral rami of the anterior and posterior nerve of each seg- 

 ment are continuous over the mid-dorsal and mid-ventral line 

 and that the dorsal and ventral rami of the middle nerve of each 

 segment as they approach the mid-dorsal and mid-ventral lines 

 break up into finer branches and anastomose with the anterior 

 and posterior nerves of the segment, making a very fine network. 



From specimens which had been cut near the mid dorsal 

 line and flattened out, I have sections showing anastomoses of 

 these dorsal rami from the dorsal setae to the dorsal pore and 

 from the ventral to dorsal seta;. 



In Allolobophora fcetida the posterior nerve from the gan- 



