350 THE SPINAL CORD BY J. GERLACH. 



treated with carmine and ammonia, sometimes present appear- 

 ances to which no other interpretation than that of Deiters 

 can be given. In the former, the bands of fibres entering the 

 grey substance as the anterior roots, run for the most part 

 towards the cell layers of the anterior cornua, which they for 

 the most part curve around. Again, fibres belonging to the 

 anterior roots can be fairly followed into the cell layers ; but 

 it is impossible to discover their relation to the cells of which 

 this is composed, because the chloride of gold and potassium has 

 scarcely any action on the nerve cells, and hence in those prepa- 

 rations where the course of the fibres is most distinctly brought 

 into view by the aid of this reagent scarcely any nerve cells 

 are to be seen. On the other hand, in longitudinal sections of 

 the spinal cord of the Calf, that have been moderately hard- 

 ened in bichromate of ammonia, then well stained and carefully 

 washed with application of gentle pressure, some of the nerve 

 processes given off from the cells may be directly observed, 

 and their course followed to a considerable extent. The direc- 

 tion pursued by these nerve processes is always horizontally 

 forwards, whilst the frequently branched protoplasmic pro- 

 cesses radiate outwards in every direction. In cases where I 

 have been unsuccessful in following one of these nerve pro- 

 cesses into the fibres of the anterior roots, its straight course 

 towards the point of entrance of the anterior roots of the 

 nerves, together with the fact that in the cervical and lumbar 

 enlargements the nerve cells become more numerous coinci- 

 dently with the increase in size of the root fibres, speak 

 decisively in favour of the view that the nerve processes are 

 to be regarded as the origins (themselves arising from the cells) 

 of the anterior root fibres. 



Far more difficult to investigate, and therefore still more 

 obscure, is the determination of the origin of the posterior roots 

 of the spinal nerves. The posterior cornua do not contain any 

 more or less sharply defined cell layer, the cells being more 

 generally distributed through a plexus of nerve fibres, and being 

 for the most part considerably smaller than those of the anterior 

 cornua ; moreover, as has been already remarked, we have no 

 means of distinguishing the smallest of these cells from the cel- 

 lular elements of the neuroglia. Deiters has indeed demonstrated 



