Cites Plate XIX, Journal of Physiology 10 (3) (1889). Figs. 1-7 from W.H. Gaskell, 'On the Relation between the Structure, Function, Distribution and Origin of the Cranial Nerves; together with a Theory of the Origin of the Nervous System of Vertebrata'.
Description:

Explanation of Plate XIX (figs. 1-7):

'Fig. 1. The supporting tissue or myelospongium of the spinal cord (copied from His).

Fig. 2. Portion of a section of the lining of the central canal in the region of the infundibulum of a puppy, to show how the original compact layers of epithelial cells spread out to form the substantia gelatinosa centralis.

Fig. 3. Section of the wall of the saccus vasculosus in the adult skate.

Fig. 4. Reproduction of Kölliker's drawing of the spinal cord of the embryo of the rabbit, to show how at this stage the dorsal part of the tube is free from the admixture of nervous material.

Fig. 5. Section of cord in chick (about 8 days) through the rhomboidal sinus to show the position of the groups of motor ganglia, and the manner in which a wedge-shaped mass of the original epithelial embryonic tissue remains on the dorsal side of the central canal free from admixture with nervous material.

Fig. 6. Appearance of this wedge-shaped dorsal mass of embryonic tissue in the more adult condition. The spaces formed by the nucleated meshwork are filled with a homogeneous gelatinous material.

Fig. 7. Section through the nervous matter forming the fimbria of a dog-fish, with its overlying membranous roof. The epithelial layer of the membranous roof is seen to be continuous with and to form the lining epithelium of the projections of nervous matter, while the pia mater as shown by the thin lines does not follow the couirse of the epithelial layer.

Fig. 8, Dorsal view of the medulla oblongata and cerebellum of a dog-fish. cb. worm of the cerebellum, l. the two lateral membranous pouches which form the roof of the commencing cerebellar hemispheres or fimbriae, d. membranous roof of the lVth ventlicle which is continuous with the two lateral membranous pouches.' (210-211)

 

Figs. 1-2 in text:

'The formation of this meshwork has been well described by His [note: 'op. cit'], who points out that it is formed by the modification of layers of epithelial cells of the same kind as those lining the central canal. The protoplasm surrounding the nuclous of the original cell thins out and elongates, forming long threads connecting together the nuclei which are now nearly denuded of their surrounding protoplasm. In Fig. 1, Pl. XIX I reproduce His' figure, which shows clearly the formation of this meshwork, to which he gives the name of myelospongium.

I also (Fig. 2, Pl. XIX) give a drawing of a portion of the substance lining the central canal in the neighbourhood of the infundibulum of a puppy, in which the limbs were fully formed and the groups of nerve cells in the cranial and spinal region is were well defined. It shows clearly the formation of the substantia gelatinosa centralis from the original layers of epithelial cells.' (192)

 

Figs. 1 and 3 in text:

'The same method of formation, with the same Structure, is found in the membranous portions of the brain already spoken of, such as the infundibular sacs of the skate and the inembranous enclosures of the fimbriae of the dog-fish, and the comparison of Fig. 3, Pl. XIX, which represents a section through a part of the saccus vasculosus of the skate, with Fig. 1 on the same Plate, shows that the membranous structure formed is in all cases the same in character as the myelo-spongium described by His, which was, as we have seen, formed from the walls of the saine embryonic tube. Especially instructive is the evidence given by the formation of the rhomboidal sinus in birds.' (197)

 

Figs. 4-6 in text:

'At first the embryonic tube is formed in the same manner in this part of the nervous system as in other places, so that Kölliker's picture of the cord of the rabbit, Fig. 4, Pl. XIX, may be used to illustrate the original relation between the nervous and non-nervous parts of the tube here as elsewhere. At a later stage we see as represented in Fig. 5, Pl. XIX, that the white matter of the cord remains separated in the dorsal region by the original layers of embryonic cells; the result being that in the course of growth this mass of embryonic tissue which is not invaded by nervous elements forms a wedge-shaped mass in between the nervous elements on each side.

This tissue is at first composed of the same kind of epithelial cells as those forming, the lining of the central canal, each cell possessing a well-defined nucleus in the midst of its protoplasmic contents so that at a period (about eight days) when the nerve cell groups of the anterior horn, the white matter of the cord and the central canal are all well formed, the appearance of a section through this region is as given in Fig. 5, Pl. XIX. Later on a peculiar degeneration takes place in these cells, which consists in the formation of a large quantity of gelatinous material which apparently, just as the fat globules in a fat cell, push the nucleus and the remainder of the protoplasm of the cell to one side, so as to give the appearance of a nucleated mesh-work, the interspaces of which are filled up with gelatinous material. This is represented in Fig. 6, Pl. XIX. At the same time in consequence of the large amount of gelatinous material, this wedge-shaped altered portion of the dorsal wall of the original tube presents the appearance in the adult bird of a jelly-like mass lying upon the spinal cord in this region.' (197)

 

Fig. 4 in text:

'According to the account given by Balfour, the white matter appears first in Elasmobranchs as a layer on the ventral and lateral parts of the spinal cord, but does not extend to the dorsal surface; at the same time the anterior white commissure is formed. About the same time two large bilateral ventral masses of nerve cells appear which are formed on the outer anterior part of the original thick walled tube as seen in Fig. 4, P1. XIX, so that at this time, before the dorsal coalescence of the walls of the canal to form the posterior fissure, the nervous elements are represented by a series of symmetrically situated bilateral ganglion masses connected together by longitudinal and transverse commissures, the whole being situated within the walls of, but ventrally to, the non-nervous tube already spoken of.' (198)

 

Fig. 5 in text:

'in crocodiles and birds at the very suirface of the lateral region of the cord a group of nerve cells exists which is as strictly metameric as the ganglion cells on the posterior roots of the spinal nerves. I have described this lateral group of cells in the cord of the crocodile in a former paper [note: 'Proc. Physiol. Soc. Dec. 12, 1886. This Journ. Vol. vii.']; and Fig. 5, P1. XIX illustrates their situation in the cord of the chick. ' (

 

Figs. 7-8 in text:

'In Fig. 8, Pl. XIX I give a dorsal view of the medulla oblongata and cerebellum of a large dog-fish to show the thin membranous roof of the 4th ventricle and its continuation into the two membranous lateral bags which overlie the fimbria. In Fig. 7, Pl. XIX I give the appearance of a transverse section through one of the fimbriae with its overlying membranous roof, to show how the epithelial lining of that roof does not follow the course of the pia mater, but passes into, blends with, and forms the lining of the nervous matter of the fimbria itself; as is also seen, proliferation of these epithelial cells appears to take place where the membranous bag, comes into close relation with the nervous substance.' (195)

 

Fig. 8 in text:

'This very formation of the worm of the cerebellum in the Elasmobranch produces of necessity the two lateral membranous folds shown in Fig. 8, P1. XIX. These in their turn become surrounded with nervous matter and then form the cerebellar hemispheres.' (208)

 

 

Cites Plate XVI, Journal of Physiology 10 (3) (1889). Figs. 1-5 from W.H. Gaskell, 'On the Relation between the Structure, Function, Distribution and Origin of the Cranial Nerves; together with a Theory of the Origin of the Nervous System of Vertebrata'.
Description:

Explanation of Plate XVI (figs. 1-5):

'Fig. 1. Portion of a section through the IlIrd cranial nerve of the dog, to show how the smallest fibres in the nerve congregate together at the periphery, preparatory to passing out into the oculomotor ganglion.

Fig. 2, Portion of a section through the middle of the oculomotor ganglion, to show that there are no large nerve fibres in the ganglion. (From the same series as Fig. 1.)

Fig. 3. Section through some of the short ciliary nerves immediately after their exit from the oculomotor ganglion. (From the same series as Figs. 1 and 2.)

Fig. 4. Section through some of the rootlets of the VIIth cranial nerve of the dog, to shot the presence of the large fibres in these rootlets.

Fig. 5. Section through the lVth cervical nerve of the rabbit at the origin of the phrenic nerve, to show the fibres of the phrenic nerve (B) separating out from the larger fibres of the IVth cervical nerve (A).' (209)

 

Figs. 1-3 in text:

'Fig. 1, PL. XVI, is a small portion of one of a series of sections taken through an osmic preparation of the IIIrd nerve of the dog. The sections were cut from the roots of the nerve towards the periphery and the section of which Fig. 1 represents a part was through the nerve just before the oculomotor ganglion was reached. Great numbers of the smallest fibres are seen coming to the periphery of the nerve, preparatory to entering into the oculomotor ganglion. Soon after this section the cells of the oculomotor ganglion begin to appear and Fig. 2, PI. XVI, represents a portion of one of the sections through the middle of the ganglion; all the fibres in among the ganglion cells are of the smallest size to be found in the IIlrd nerve. The continuation of the series of sections shows the formation of the short ciliary nerves from the ganglion, and as is seen in Fig. 3, PI. XVI, the fibres of which these nerves are composed are all very small and very uniform in size.' (164)

 

Fig. 3 in text:

'The reason then why the nerve cells with which the fine fibred motor nerves of the sphincter and ciliary muscles are connected are of the spinal type is because the fibres do not lose their medullary sheath in their passage through the ganglion; as is seen in Fig. 3, P. XVI, the short ciliary nerves are medullated as much as the small fibres in the roots of the oculomotor nerve which give origin to them.' (165)

 

Figs. 4-5 in text:

'In Fig. 5, PI. XVI, I give a section through the 4th cervical nerve of the rabbit at the point where the fibres of the phrenic are separating out from the rest of the fibres of the 4th cervical nerve; as is seen the fibres of the phrenic nerve (B) are very uniform in size and much smaller than the large motor fibres of the somatic muscles supplied by the 4th cervical nerve (A). If then any somatic fibres from the nucleus of the VIth passed out in the VIIth nerve they ought to be conspicuous by their size among the smaller motor fibres of the VIIth. Reasonino in this way I was much struck to find that in the roots of the VIIth nerve of the dog a small group of large fibres stands out most conspicuously; the size of the fibres being the same as those of the large motor nerves of the eye muscles, viz. 16µ-18µ. In Fig. 4, P1. XVI, these fibres are shown in the rootlets as they are found. Here then appeared to be positive evidence of the existence of somatic motor fibres in the roots of the VlIth nerve. Upon examination, however, of the nerves supplying the orbicularis and frontalis muscles I was unable to find that their fibres were different in size to those of the other facial muscles, and, indeed, section of the branches of the VIIth nerve after they had passed out of the stylomastoid foramen failed to show the presence of any group of especially large fibres.' (174-175)

Cites Plate XVII, Journal of Physiology 10 (3) (1889). Figs. 1-4 from W.H. Gaskell, 'On the Relation between the Structure, Function, Distribution and Origin of the Cranial Nerves; together with a Theory of the Origin of the Nervous System of Vertebrata'.
Tags: osmic acid
Description:

Explanation of Plate XVII (figs. 1-4):

'The sections are all carefully drawn from osmic acid preparations of the nerves of man.

Fig. 1. Transverse section of rootlet of IIIrd cranial nerve to show degenerated ganglion. (Zeiss A, Oc. 4.)

Fig. 2. Three transverse sections of IVth cranial nerve. (Zeiss A, Oc. 2):

a. Section near exit of nerve from valve of Vieussens, showing degenerated tissue arranged so as to form a sheath around the functional medullated nerve-fibres.

b. Section of nerve farther away from point of exit, showing the formation of the degenerated galglion.

c. Section of nerve peripheral to the ganglion. The degenerated tissue has almost entirely disappeared.

Fig. 3. Transverse section of VlIth cranial nerve to show degenerated ganglion. (Zeiss A, Oc. 2.)

Fig. 4. Longitudinal section of a rootlet of IlIrd cranial nerve to show the structure of the degenerated material. (Zeiss D, Oc. 2.).' (209)

 

Figs. 1-2 in text:

'In Pl. XVII, Fig. 2, I give three sections of the IVth nerve selected out of the whole series. The section (2a) is through the root of the nerve close to its exit from the valve of Vieussens, and it shows that the nerve fibres are surrounded by a thick sheath of peculiar connective-tissue-like material; while section (2c) taken more towards the periphery shows that this sheath of peculiar tissue no longer exists. An examination of the sections between 2a and 2c shows that the manner of disappearance of this thickened sheath is very peculiar, it does not remain on the outside of the nerve fibres but forms roundish masses of the same -peculiar material in between the nerve fibres themselves as is seen in (2b), so that the sections with a low power possess a remarkable resemblance to a section through a ganglion. At the peripheral side of this ganglion- like formation these round masses of fibrillar-like material cease somiewhat abruptly and the sections appear as in 2c. Again in the IlIrd nerve the same formation is seen; here we have a nerve composed of a great numnber of rootlets and the sections show that the ganglion-like structure makes its appearance on the separate rootlets before they join together to form the conjoint root. Very striking indeed is the sight of a number of these rootlets each presenting in a greater or less degree the appearance represented in Fig. 1, PI. XVII. Here too we see another point of resemblance between this structure and a spinal ganglion. In the latter it is of common occurrence to find that the formation of the ganglion has thrown many nerve fibres out of their previously parallel course, so that on transverse section of the ganglion many fibres are cut in a more or less longitudinal direction; the same deviation is found, as is seen in Fig. 1, in many of the large, fibres of the IIIrd nerve, which are thrown out of their direct course in consequence of the formation of these rounded fibrillar masses in a way precisely similar to what occurs in the spinal ganglion.' (167)

 

Fig. 2 in text:

'In the Elasmobranch, as for instance the dog-fish... we find in the infundibular region a membranous sac known as the saccus vasculosus, the membranous roof of the 4th ventricle is more extensive than in the mammal, the choroid plexuses are very conspicuous as is shown in the diagram Fig. 2, P1. XVIII.' (194)