352 THE SPINAL CORD, BY J. GERLACH. 



cornua, but has made no statements in regard to the direction 

 they pursue. I have also observed these small cells, which 

 are situated behind the cell layer of the anterior cornu, in that 

 portion of the grey substance which can neither be held to 

 belong to the anterior nor to the posterior cornu, to be pro- 

 vided with nerve processes ; but have noticed in longitudinal 

 sections, treated with carmine and ammonia, that the nerve 

 processes of these cells also constantly run horizontally for- 

 wards ; hence these smaller cells, like the larger ones of the 

 anterior cornua, are to be regarded as points of origin of the 

 fibres of the anterior roots. If we consider further that the 

 number of actually visible nerve cells in the posterior cornua 

 is smaller than in the anterior, whilst the anatomical fact has 

 long been known that the posterior roots of the nerves are 

 thicker than the anterior, and at the same time contain much 

 finer fibres, and that consequently the number of fibres leaving 

 the spinal cord by way of the posterior roots is much greater 

 than by the anterior, it appears very improbable that the 

 fibres of the posterior roots should have the same relations, as 

 regards their origins, as the anterior. On the other hand, the 

 frequent subdivision of the smaller nerve fibres, especially in 

 those parts of the posterior cornua that lie immediately in 

 front of the substantia gelatinosa, seems to demonstrate that 

 the fibres of the posterior roots are not directly continuous 

 with nerve cells, but penetrate immediately into the delicate 

 nerve-fibre plexus of the grey substance, through the inter- 

 mediation of which the relations between the fibres of the 

 posterior roots and the nerve cells are established. If this 

 view be correct, and many appearances obtained from pre- 

 parations stained with chloride of gold are in favour of it, a 

 fundamental morphological distinction exists between the two 

 physiologically different species of root fibres. 



In regard to the second of the above-mentioned questions, 

 referring to the ultimate relations of the protoplasmic pro- 

 cesses, an observation made by Deiters * may here be noticed, 

 to the effect that the finest branches of these processes 

 are sometimes invested by a dark-edged double contour, and 



* Loc. tit., p. 65. 



