STRUCTURE OF NERVE CELLS. 



597 



paratively open meshes in most parts of the cell, but sometimes more 

 closely arranged immediately around the nucleus. The cell network is 

 continuous with fibrils in the cell processes (Fig. 304). 



Apathy 1 has shown that cells which are apparently unipolar 

 (unineural), may show, when appropriately stained, a central fibril in the 

 centre of the nerve fibre process, which is traceable from a network of 

 fibrils encircling the nucleus, and two or more fibrils situated peri- 

 pherally in the process and connected with another network, inter- 

 communicating with the first, and situated at the periphery of the 

 cell (Fig. 302 A). He suggests that the 

 central fibril is efferent, the others afferent 

 in function. 



A fibril network of a somewhat similar 

 character has also been demonstrated by 

 Golgi 2 in various cells of the central 

 nervous system and in the cells of the 

 spinal ganglia of mammals, so that the 

 existence of such a network is probably 

 to be looked upon as of general occurrence. 

 Apathy's observations in annelids go, how- 

 ever, further than this, for he has been 



able to Show that the fibrillse which he FlG 303.-Spinal. ganglion cell, 



describes are not only continuous through- 

 out the whole of any one nerve cell and its 

 processes, but exhibit continuity from cell to cell, and form a network 

 in the intercellular substance, or grey matter, of the nerve centres. If 

 this should prove to be the case in vertebrates, as Nissl inclines to 



showing intracellular network of 

 fibrils. 0. Golgi. 



FIG. 304. Nerve cell of annelid, showing neuro-fibrils within the cell- 

 body, df, fibrils of dendrons ; mf, fibril of axon. The two sets of 

 fibrils form a network within the cell. 



believe, 3 our conception of the nervous system must undergo important 

 modification. At any rate, it appears clear that, at least in annelids, 

 the neurone theory will not hold good, although the structure and 



2 Boll. d. Soc. med.-chir. di Pavia, Milano, 1898, Fasc. 1, and Hid., 15 Luglio 1898. 

 Cf. Donaggio, Riv. sper. di freniat., Reggio-Emilia, 1896, p. 265 ; Martinotti, Ann. di 

 freniat., Torino, 1897 ; E. Holmgren, Anat. Anz., Jena, 1899, Bd. xvi. S. 161. 



3 Nissl, Milnchen. Med. Wchnsclir., 1898, Bd. xlv. S. 988. Cf. also Bethe, Arch. f. 

 mikr. Anat., Bonn, Bd. 1. and H. 



