308 LECTURE XIII. 



the granular and bacillar layers of the retina (Fig. 91) 

 which I have brought before your notice. For here too 

 we find branched, almost arborescent filaments, which 

 bear upon them minute granules, often in several rows, 

 and attach themselves to the ganglion-cells in a manner 

 essentially differing from, and much more delicate than 

 that observed in the case of the proper nerve-processes. 

 This kind of ganglion-cells may very likely stand in some 

 close connection with the psychical functions, but at pre- 

 sent we have no accurate information upon the subject, 

 and it will, I expect, still be a long time before anything 

 positive can be made out about it, seeing that parts which 

 are much more accessible to investigation, like the retina, 

 present the very greatest difficulties to those who seek 

 to discover the functions of the individual segments. 



The conformation which we have found to exist in the 

 spinal marrow of man is essentially the same throughout 

 the whole series of vertebrate animals, only that in man 

 it is generally more complicated, and exhibits a greajter 

 abundance both of nerve-fibres and ganglionic matter. I 



FIG. 92. 



Fig. 92. Transverse section through the spinal marrow of Petromyzon fluviatilis. 

 F, Anterior fissure, F', posterior fissure, c, central canal with epithelium, gm, large 

 many-rayed ganglion-cells with processes in the direction of the anterior roots, 

 gp, smaller, many-rayed cells with processes running to the posterior roots, gs, large, 

 roundish cells in the neighbourhood of the posterior commissure (sympathetic cells). 

 %, n. Transverse sections of the large, pale nerve-fibres (Miillerian fibres), n\ gaps 

 out of which the large nerves have gallen ; n", gaps belonging to smaller fibres. 

 Besides, the cut ends of numerous finer and coarser fibres. 



