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 I (figs. 1-5):

'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. 1. Transverse section of the splenic nerve of an ox given by Kölliker, loc. cit. p. 35 (strongly magnified).

Fig. 2. Fibres of Remak from the internal carotid branches of the superior cervical ganglion of a rabbit. Teased in iodised serum: (a) nucleus, (b) core of the fibre inside its sheath.

Fig. 3 a. Transverse section of the splenic nerve of an ox. Osmic acid 1 per cent. Haematoxylin chinolin: (a) nucleus, (b) core of fibre of Remak.

Fig. 3 b. Two fibres of Remak from the vagus of rabbit. To show distinctness of sheath in isolated fibres. 1 per cent. osmic acid. Haematoxylin.

Fig. 4 a. Teased preparation of a bundle of fibres of Remak from the carotid canal of a rabbit. Corrosive sublimate. Hamatoxylin and chinolin: (a) nucleus, (b) fibre of Remak, (c) bundle of fibres.

Fig. 4 b. Isolated fibres of Remak from the same preparation.

Fig. 5. Fibres of Remak from the splenic nerve of an ox. Golgi's method, twice repeated: (a) varicosities on fibre, (b) shrunken part of fibre.' (309)

 

Figs. 1, 3, 5 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. 1, 4 and 6 in text:

'if a fibre of Remak in transverse section shows such a distinct structure and well-marked outline, it may well be asked, How is it that Key, Retzius, Schiefferdecker and Kölliker have all described fibres of Remak as consisting of bundles of fibrillae? And, undoubtedly, in teased preparations of hardened non-medullated nerves, the fibres of Remak are nearly always seen to be breaking up into fibrillae, as may be seen in Figs. 4 a, 4 b, 6. Further, in transverse sections, a dotted fibrillar appearance is of very frequent occurrence: such an appearance is shown by Fig. 1.' (278)

 

Fig. 1 in text:

'How are the appearances seen in transverse sections of nonmedullated nerves, such as Fig. 1, to be explained, if fibres of Remak do not consist of bundles of fibrils closely placed together?' (276)

 

Fig. 2 in text:

'Having thus given above the various views held as to the structure and nature of fibres of Remak, and also the points of enquiry to which the same lead, I shall most fitly introduce my own observations by describing the appearance and size of fibres of Remak in the fresh condition. If a piece of the splenic nerve of an ox, or the internal carotid branches of a rabbit's superior cervical ganglion, are taken from the body as quickly as possible after death, and then teased in a little aqueous humour or iodized serum, there are seen fibres having a diameter of about 1.5 to 2µ, with nuclei along their course (Fig. 2). These obviously correspond to the fibres described by Remak, and so in the rest of this paper I shall consider that a fibre of Remak has a diameter of 1.5 to 2µ, or a little more. The fibres can be seen to be slightly granular, and to swell out somewhat where the nuclei occur, which can only just be seen as pale, ill-defined structures about 16µ long and 4µ in diameter.' (277)

'with reference to the core of the fibres, I have tried Kupffer's acid-fuchsin method several times and I always find that the sheaths of the fibres are stained quite as deeply as the dots which appear in the core of the fibres. But what is still more striking, a great number of the fibres do not show any dots in the centre at all: others show two, three, or even four dots, while others, instead of dots, exhibit a sort of ill-defined granularity (Fig. 18).

These appearances, in fact, correspond to the granular appearances of fibres of Remak, teased out in iodised serum (Fig. 2). For the core of the fibres is but a process of a nerve-cell, consisting, of rather fluid undifferentiated protoplasm, which is probably granular or, at least, under the influence of osmic acid becomes granular, since nerve-cells after osmic acid hardening are full of granules.' (284)

 

Fig. 3 in text:

'It will be found that the fibrillae into which the fibres in teased preparations break, have the staining properties of the outer part of the fibre. This is just what would be expected from the appearances seen in transverse sections of a piece of nerve undergoing post-mortem changes; and, as a mnatter of fact, many of the preparations of nerves showing fibrillar fibres of Remak, may be explained in this way. Again, it can be seen from transverse sections (Fig. 3) how closely the fibres of Remak adhere to one another; consequently, if a non-medullated nerve be teased after being fixed, the mere mechanical teasing apart of the fibres with the points of the teasing needles greatly assists in giving them a fibrillar appearance.' (280)

 

Fig. 5 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)