Dark or Double-bordered Nerve Fibre. 201 



accord altogether with the existing views of other investigators; 

 but, on the contrary, differ from them in many respects. It may 

 be supposed, therefore, that my statements will be subjected to sharp 

 criticisms from many sides ; but knowng that the researches and 

 observations forming the subject of this treatise were not made in a 

 careless or superficial manner, I feel no hesitancy in placing them 

 before the medical public in general, and my collaborators in par- 

 ticular. 



All points which are at present considered as established facts 

 I have avoided as much as possible, except in cases where the 

 demonstration demanded a combination of the old with the new. 



The more or less favourable results of all scientific investigations 

 depend, as is known, to a certain extent upon the advantageous 

 application of the means employed. I will consequently devote a 

 short space to a few premonitory remarks, relating to the mode of 

 investigation followed in my labours. 



In microscopical examinations, the success does not alone depend 

 upon a careful and correct preparation of the tissues to be examined, 

 but it is quite as important to illuminate them in such a manner as 

 to enable the eye to recognize the details of their construction. 



fibre, on which all its parts are distinctly recognized ; b and c, fragments of axis 

 cylinders, drawn out and partially torn by the needles during the manipulation. The 

 granular-fibrillous structure is distinctly seen on these specimens. Maguf. 720 diam. 



Fig. 14, Pl. LXII. — Processes of a ganglionic body of the spinal marrow of 

 man, having remained twenty-four hours in a weak chromic acid solution ; on two 

 of the ramifications some fibrils are seen to pass directly from one branch to 

 the other. Magnf. 465 diam. 



Fig. 15, Pl. LXII. — Ganglionic body of the cortical layer of the cerebrum of 

 man, taken from the margin of a thin section previously hardened in a solution 

 of chromic acid. On this specimen the granular-fibrillous structure is also dis- 

 tinctly seen ; the terminal ramifications of the long-pointed process belong to the 

 terminal nervous network of the cortical layer. Magnf. 720 diam. 



Fig. 16, Pl. LXI. — Nerve fibres of tije spinal marrow of man, with denuded 

 axis cylinders ; a, varicose fibre, the axis cylinder of which consists only of one 

 granular fibril ; 6, straight fibre of the same size ; c, fibre, the axis cylinder of 

 which shows only two fibrils. Magnf. 7^0 diam. 



Fig. 17, Pl. LXII. — Fragment of the ramifications of a ganglionic body of 

 the spinal marrow of man (fresh specimen treated with a very weak solution of 

 chromic acid). Maguf. 970 diam. 



Fig. 18, Pl. LXI. — Fine terminal ramifications of a nerve fibre, coming from 

 one of the lateral processes of a ganglionic body of the cortical layer of the cere- 

 brum of man. Magnf. 720 diam. 



Fig. 19, Pl, LXII. — Diagram, representing an axis cylinder on a large scale. 



Fig. 20, Pl. LXI. — Axis cylinder of the spinal marrow of man, denuded of its 

 coverings; on one point it has been pressed flat by the point of the needle. 

 Magnf. 720 diam. 



Fig. 21, Pl. LXII. — Denuded axis cylinder of the spinal marrow of man, with 

 folded sheath. Magnf. 720 diam. 



Fig. 22, Pl. LXI. — Nerve fibre from the anterior horns of the grey substance 

 of tlie spinal marrow of man, showing the origin of the fibrils of the fibrillous 

 layer from the sheath of the axis cylinder. Magnf. 720 diam. 



The various parts of the nerve fibres and ganglionic bodies in the above 

 figures are represented as more or less illuminated with oblique light. 



