Dark or Douhle-hoi'dered Nerve Fibre. 217 



on which no sheath is any more to be seen (Fig. 16). The contours 

 of these, namely, do not appear as straight Hnes, but as a row of 

 small convexities, each of which is produced by a projecting granule. 

 "With obKque illumination, the whole row of granules may already 

 be recognized with an amplification of 500 diameters. With one of 

 700 diameters, or even higher (Fig. 17), the granular structure of 

 the fibrils is placed beyond doubt. On the finest ramifications 

 of some processes of the ganglionic bodies of the cortical substance 

 of the brain, or in the terminations of fine nerve fibres in its nervous 

 network, the granular nature is unmistakable (Fig. 15). 



The fibrils of the axis cyhnder extend through the processes of 

 a ganglionic body over its surface. A considerable number of them 

 connect the processes with each other, i. e. a part of the fibrils of one 

 process arriving at the ganglionic body, pass over its surface and 

 take part in the formation of other processes. The com'se of the 

 rest I must leave untouched for the present. 



In the axis cylinders the fibrils are arranged closely to each 

 other. But this is not the case with the thicker processes, in which 

 they are placed more loosely alongside of each other (Fig. 14) ; 

 accordingly, single fibrils are frequently observed on the torn ends 

 of these processes, reaching a little distance beyond their neighbours, 

 and afibrding one an opportunity of becoming convinced of their 

 granular-fibrdlous structure. Arriving at the roots of the processes, 

 the fibrils diverge in their course, to pass, as already mentioned, in 

 various du-ections over the surface of the ganglionic body. At this 

 separation, however, the entire process does not become divided into 

 single fibrils, but it seems rather that the latter separate from each 

 other in pairs, in which form they are also observed on the surface 

 of the ganglionic body, especially along its margin.* On torn 

 ganghonic bodies, it may be further observed, that these pairs of 

 fibrils may also become broken in a longitudinal direction into pairs 

 of granules, so that groups composed of four granules may be 

 formed. In examining, therefore, the surface of a ganglionic body 

 illuminated obliquely, with an ampHfication of 70U diameters, it will 

 appear to be composed of minute groups of granules. This is 

 especially the case on specimens prepared with a solution of chromic 

 acid ; on fresh ganghonic bodies, however, these groups of granules 

 appear almost as so many minute polygonal bodies with a dark 

 point in the centre. As such I had also regarded them until a year 

 ago, when by a careful re-examination of the subject I found that 

 the ganglionic bodies, as well as the processes proceeding from them, 

 were composed of the same fine granular fibrils as the smaller axis 

 cylinders. 



* This separation may perhaps also take place in the form of small bundles 

 composed of three or four fibrils, which is, however, difficult to determiae, as never 

 more than two are presented to view. 



