204 Eelation of Nervous System to the Developinfr Musculature 



to be present. They were, of course, rejected as being open to the sus- 

 picion that the nervous influences had not been entirely eliminated. 

 In none of the larvse without spinal cord was there ever any response to 

 the direct mechanical stimulation of the muscles to be observed with cer- 

 tainty. On the other hand, in the one case (R. palustris) in which elec- 

 trical stimulation was tried, a marked local contraction of the axial 

 musculature at the root of the tail followed the application of the elec- 

 trodes at that point. This indicates that the musculature in these in- 

 stances is capable of functioning. The case is, however, not quite con- 

 clusive, because no 

 complete . microscopic 

 examination was made, 

 the specimens having 

 been severely injured 

 during the stimulation. 

 The examination of 

 specimens in serial 

 sections demonstrates 

 clearly that the effect 

 of the operation is to 

 remove permanently 

 the spinal cord from 

 the greater part of the 

 trunk and tail. Only 

 the small portion at 

 the tip of the tail is 

 present. This part of 

 the medullary cord is, 

 however, in normal as 

 well as in injured specimens, merely an epithelial tube containing 

 no ganglion cells and giving rise to no peripheral nerve fibers. Ko 

 regeneration of cells takes place from the anterior portion of the cord. 

 The cut end is found to be rounded off and the ventricle entirely closed. 

 The nerve fibers constituting the longitudinal bundles extend, however, 

 in all cases examined, for a considerable distance beyond the limits of 

 the cord. They leave its posterior end and pass in a caudal direction 

 through the mesenchyme occupying the small space bounded by the myo- 

 tomes, notochord and epidermis. These bundles are thick and very dis- 

 tinct as they emerge from the cord; sometimes they break Up into small 

 bundles and in several instances distinct fasciculi could be traced into the 

 lateral branch of the vagus. The bundles gradually become thinner as 



Fig. (>. Same specimen as in Fig. 4. Six days after the 

 operation. X 9^2- 



