Cited by I.L. Tuckett, 'On the Structure and Degeneration of Non-Medullated Nerve Fibres', Journal of Physiology 19 (4) (1896), pp. 267-311.
Description:

Explanation of Plate II (figs. 6-13):

'Figures 2, 3a, 3b, 6, 7, 8, 9, 10, 11, 12, 13a, 13b, 14, 17, 18a, 18b, 19, 20, 21a, 21b, 21c, 21d, 21e are drawn with camera lucida and ocular 4, objective V Leitz, magnification 850 diams.

Figures 4a, 4b, 5, 13c, 13d, 15a, 15b, 16a, 16b, 16c, 16d, 16e are drawn with camera lucida and ocular 4, objective 7 Leitz, magnification 590 diams. 

All the figures with the exception of 18 a and 18 b are reduced by 1/3 from the original magnification. The shades of colour in the specimens are represented in the figures as nearly as may be, but it is difficult to get an exact reproduction of the various shades of blue produced by Delafield's heematoxylin and chinolin, Grübler's haematoxylin, methylene blue.' (309)

'Fig. 6. Fibres of Remak from the carotid canal of a rabbit: teased in aqueous humour, fixed in 1 per cent. osmic acid. Grübler's haematoxylin and eosin in glycerine. These fibres, being somewhat flattened through teasing and crushing, show how the sheath breaks into fibrils: (a) nucleus, (b) core of fibre, (c) sheath.

Fig. 7. Transverse section of splenic nerve of ox. Corrosive sublimate. Haematoxylin and chinolin: (a) nucleus, (b) shrunken part of fibre, (c) varicose part of fibre.

Fig. 8. Transverse section of splenic nerve of ox. 2 per cent. ammonium bichromate several months. Heematoxylin and chinolin: (a) varicose part of fibre, (b) shrunken part.

Fig. 9. The outer edge of a transverse section of the splenic nerve of ox. 1 per cent. osmic acid. Heematoxylin: (a) nucleus indented by core of fibre of Remak, (b) fibre of Remak.

Fig. 10. The same section but nearer the centre: (a) varicose part of fibre, (b) shrunken part of fibre.

Fig. 11. Outer part of a transverse section of the splenic nerve of ox. Osmic acid .5 per cent. Haematoxylin: (a) nucleus, (b) varicose part of a fibre, (c) shrunken part of a fibre.

Fig. 12. The same section but at the centre of it: (a) nucleus, (b) shrunken part of fibre, (c) varicose part of fibre, (d) place where some fibres have broken up.

Fig. 13 a. Fibres of Remak from the carotid canal of rabbit. .06 per cent. methylene blue in .6 per cent. salt solution.

Fig. 13 b. Similar fibres treated with methylene blue in aqueous humor.

Fig. 13 c. Fibres of Remak from the splenic nerve of ox. .06 per cent. methylene blue in .6 per cent. salt solution. Preserved by Bethe's method [Archiv für mik. Anat. XLIV. 579. 1895]. Mounted in Canada balsam.

Fig. 13 d. Similar fibres preserved by Bethe's method mounted in glycerine.' (309-310)

 

Fig. 6 in text:

'it is also true that if a piece of fresh nerve be carefully teased out in aqueous humour and crushed under a cover slip and then fixed immediately with 1 per cent. osmic acid, the fibres of Remak will still often have a fibrillar appearance (Fig. 6). If these fibres, however, be stained with warm fuchsin for 15 minutes, and then stained with haematoxylin to bring out the nuclei, there will be seen besides the deeply stained nuclei and fibrils, an almost colourless structure with a granularity like ground glass about 1 or less in diamieter, running between the fibrillae. This is, in fact, the inner part or core of the fibre.' (280)

'fibres can sometimes be seen which have not split up, and in this case they are found to be cylindrical and to have a diameter of 1.5µ to 2µ, whereas, when they split into fibrils, the fibrils spread out and give the fibre a flattish appearance and an apparent diameter of 3µ or even 4µ [note: 'Cf. Key and Retzius' description of fibres of Remak (p. 270 supra).']. This appearance of intact cylindrical fibres of Remak is shown in Fig. 14 and should be contrasted with the crushed fibres shown in Fig. 6.

This Fig. 14 brings me at once to the question of the nuclei, for here there can be no doubt that the nuclei are inside or embedded in the outer part of the fibre. This is seen here so clearly because the nuclei have been very lightly stained. If, as is usually the case, they are stained deeply, as in Fig. 6, they come out so much more prominently than the rest of the fibre that they stand out and appear to lie on the surface of the fibre.' (280-281)

 

Figs. 7-13 in text:

'I have found that if a piece of the splenic nerve [note: 'I take a splenic nerve, as it is the nerve from which non-medullated fibres are usually obtained, and which is figured by nearly all authors.'] of an ox be put into a fixative reagent within ten minutes of death (this means putting the nerve into the reagent at the slaughter-house itself) then, no matter what the reagent be, if its fixative power be great enough, the appearance in transverse section will be more characterized by the presence of circles such as I have described in Fig. 3, than by the presence of dots; though it is true that with any other reagent but osmic acid, the circles will not be nicely defined and of uniform diameter, but distorted. Figs. 7, 8, and 11 show such appearances.

Secondly, if a piece of splenic nerve is taken from a spleen while still warm after death, but not till some 30 minutes or longer have elapsed (which is usually the case if the nerves are not taken from the spleen till it has been brought from the slaughter-house to the laboratory) and is then put into a fixing reagent, it is more than probable that a transverse section will show an appearance of dots, as in Figs. 1, 11, and 12.

The process that has been taking place can be beautifully seen, if rather a large piece of nerve is taken and put into *5 per cent. osmic acid. For here, if a transverse section be made, all around the outside of it will be seen circles of uniform diameter, such as have been described in Fig. 3, more towards the centre of the section will be seen the same circles, but some much larger while others are much smaller, till they appear almost as dots. 

And, lastly, at the centre of the section will be seen the result of this process carried on one stage further. For here some of the circles have got so large that they have burst, the outer part of the circles which stains deeply breaking up into fine fibrils, while the inner part staining but slightly is not very apparent, but can, nevertheless, be seen to be mixed up with the fine fibrils into which the outer part of the fibres bas broken. Besides these fine fibrils will also be seen nuclei and large dots which are the circles which have become smaller. In other words, a post-mortem change under the influence of the reagent has taken place. The fibres of Remak have been properly fixed at the outside of the piece of nerve. Further in, where the reagent has taken longer to penetrate (i.e. in weaker solutions with less fixing power), the fibres have become varicose, and in the centre of the nerve the fibres have burst at the varicosities, and here the outer parts of the fibres have split into fibrils letting the core escape, while between the varicosities the fibres have shrunk so as to appear as rather large dots in transverse section. Figs. 9, 10, 11, 12, show this process in its progressive stages. All this is, in fact, nothing but the post-mortem changes which take place in non-medullated nerves; and that this is the right interpretation, is clearly shown by two other methods of staining the nerves.

1. If a large piece of nerve be treated by Golgi's silver chromate method, or rather Ramon y Cajal's double impregnation variety of it, and longitudinal sections be made of the same, then the fibres of Remak come out as most distinct and sharply limited, but, at the same time, most decidedly varicose structures. Some of the valicosities may be as large as 5 µ. Fig. 5 is from such a section.

2. If, again, a piece of nerve be teased in a single drop of .06 per cent. solution of methylene blue in .6 per cent. salt solution, then many of the fibres are seen to be markedly varicose, as is shown in Fig. 13a.

From all these appearances then, it is certain that through diffusive changes taking place in the dying tissue, the fibres of Remak swell up in places so as to become varicose; or, rather, that the part which stains with methylene blue, which, as I shall show shortly, is the core of the fibres, becomes varicose while the outer part of the fibres mechanically follows the excursions of this inner part. Consequently Fig. 1 or 12 is but the appearance which a piece of nerve that has undergone extreme post-mortem changes, shows in transverse section.' (278-280)

 

Figs. 9 and 13 in text:

'The question now arises: With what part of the fibre are they connected? With the inner core of the fibre of Remak, or with the outer part which stains well, and readily splits into fibrils? There can be no doubt that they are in connection with the outer part of the fibre, and that the two together form a sheath for the inner core which is the process of a nerve-cell and carries the nervous impulse. 

The reasons for this view, which are as follows, prove at the same time that the part of a fibre of Remak which stains with methylene blue is the core.

(1) If a nucleus be detached, more often than not ragged fibrils from the outer part of the fibre are seen clinging to it. 

(2) When a piece of nerve is stained with a solution of methylene blue in aqueous humour, the fibres which appear are uniformnly cylindrical, with a diameter of about 1µ (Fig. 13 b), and they show no swellings indicating nuclei such as do the fibres in Fig. 14. Therefore the nuclei must be outside this fibre staining with methylene blue, which must, consequently, be the core of a fibre of Remak. 

(3) When the fibres of Remak are brought out by Golgi's method (Fig. 5), or by a solution of methylene blue in .6 per cent. (Fig. 13 a), salt solution, varicosities appear on them as we have seen. But these varicosities are of such a size and shape that they could not contain the nuclei. Therefore the nuclei must be outside the core of the fibre in which is deposited the silver chromate precipitate. 

(4) A transverse section of fibres of Remak shows that the nuclei are in connection with the outer paxt of the fibres rather than with the inner core, for the outer part of the fibre is sometimes seen to proceed from the edges of the nucleus over the core, which often makes a groove in the nucleus (Fig. 9), as it passes by it.

(5) If, as Ranvier directed, a piece of splenic nerve be left in ammonium bichromate for several months, then the fibres of Remak are found to be very varicose: if now they are stained for two days with hematoxylin, the nuclei and the outer part of the fibres are stained to excess;.that is, have become almost black, while the core has at length after two days taken up a certain amount of stain and come out fairly distinctly (Fig. 15). It is now found that the core is varicose and quite independent of the nuclei, while the outer part of the fibres, much broken into fibrillae, adheres to the nuclei.' (281-282)