xiv Journal of Comparative Neurology. 



in the spinal cord nor in special ganglia bat in the skin, of which they 

 form a part. The sensory fibers originate in the integument, thence they 

 pass to the cord, the dendritic mesh-work of which they penetrate. Here 

 they bifurcate forming a descending and an ascending branch as in verte- 

 brates; these branches pass strictly longitudinally and terminate free in the 

 next ganglion. The individuality of the fibre is not lost and but few if 

 any lateral branches appear. Each sensory fibre comes into connection 

 with three ganglia, the ganglion of entrance and that cephalad and caudad 

 of it." 



Thus we find in the invertebrates the real clue to the distinction 

 between motor and sensory cells and the explanation of the pregnant dis- 

 covery of Professor His, already referred to in this journal, that the sensory 

 fibre develops centripetally and the ganglia arise from a distinct epider- 

 mal embryonic anlage. The sensory cells were primarily scattered over 

 the body in a more or less heterogeneous manner and their processes were 

 distributed to the spinal nerve centres after the manner of the neuro- 

 muscular processes of Hydra. The formation of sensory ganglia is a late 

 acquisition and what was once a unipolar cell becomes by reason of its 

 retreat from the surface bipolar. 



It should be added that the application of the Golgi method is not 

 necessary to make out these relations. Prior to the appearance of this 

 paper Mr. Turner, at my suggestion, applied the sublimate modification 

 of the hsematoxylin stain to the staining of sections of Lumbricus and we 

 were able to make out even in quite thick and imperfectly hardened prep- 

 arations the peripheral nerve cells and termini. It is my impression that 

 they are much more abundant cephalad and differ in no way from the 

 beaker-masses in the pharyngeal cavity where they are very abundant. 

 The accompanying figures will make the relations obvious. (See Plate XI.) 



Fig. 5, is a section through the epidermis with impregnated nerve 

 cells. The mucous cells are large and supplied with pores while the 

 nerve cell is slender with a basal process. A capillary loop enters the 

 epidermis. Fig. 6. Part of a cross-section, a, epidermis, b, concentric 

 muscles, c, longitudinal muscles, d, spine, e, cephalic root of a double 

 nerve, _/i cross section of ganglion with an impregnated motor cell. 



Fig. 7. Horizontal section of ventral nerve cord to show the course 

 of the sensory nerve-fibers. 



The application of the Golgi method to the cerebellum has been 

 attempted by Fusari in the case of the Teleosts and the results are dis- 



