170 LOCALIZED ELECTEIZATION. 



tudinal section of a spinal ganglion in the cervical region, and 

 whicli has been heliographed after a direct photograph of 21 

 diameters, is an example. We see, in this figure, that the cells 

 are collected in great numbers towards the walls of the gang- 

 lion (an anatomical arrangement that I have found in all the 

 sections of spinal ganglia, whether longitudinal or transverse, that 

 I have made). It will be remarked that, towards the free margin 

 a a of this longitudinal section, nearly all the cells are apolar (their 

 circular form is distinct), while on the opposite side, h h, in the 

 vicinity of the posterior root, the cells are bipolar and unipolar, 

 as shown by their pear-shaped or oval outline. Well, sometimes 

 the reverse is the case ; which proves that the appearances depend 

 upon the chance of the section having been made through a 

 greater or less number of such or such cells. It is difficult to say, 

 even approximatively, what is the proportion of bijjolar or uni- 

 polar cells, for sometimes the number of bipolar cells is the 

 greatest, sometimes the contrary ; and it is, moreover, conceivable 

 that cells which appear to be apolar in a given section, may be 

 bipolar in reality. 



Kdlliker says also : — " Even where a cell gives off two pro- 

 longations, it does not follow that one of them must be centripetal, 

 and the other centrifugal : on the contrary, both may be directed 

 towards the periphery ; at least this is what is seen in examining 

 very small ganglia. Stanuius himself found, in bipolar cells, the 

 two prolongations uniting the one with the other." ^ 



In not one of my longitudinal sections of spinal ganglia, have I 

 met with this peripheral direction of the poles of bipolar cells. 

 The poles always extend in opposite directions, one towards the 

 cord, the other towards the surface, as shown in fig. 44, drawn 

 from a photograph taken from nature to 200 diameters, at the 

 point c of fig. 43, which, as already described, represents a photo- 

 graph, to 21 diameters, of a spinal ganglion. Fig. 44 shows an 

 apolar cell, a, two small unipolar cells, h, V, and two large bipolar 

 cells, c, c. 



All my transverse sections of sj)inal ganglia have shown a certain 

 number of cells that were each in communication with another 

 cell, more or less near to them, by means of a lateral prolonga- 

 tion, the texture of which, at least, was in all respects like that of 

 the central or peripheral prolongations; the lateral prolongation, 

 arising from the middle portion of the cell, appeared to be a sort 

 of nucleated sheath, which was continuous with the nucleated 

 reticular envelope of the cell. I think I am entitled to conclude. 



■' KoUikcr, loc. rii., p. 357. 



