Abstract from notes on the minute structure of the spinal cord / by John B. Trask.
- John Boardman Trask
- Date:
- 1860
Licence: Public Domain Mark
Credit: Abstract from notes on the minute structure of the spinal cord / by John B. Trask. Source: Wellcome Collection.
Provider: This material has been provided by the National Library of Medicine (U.S.), through the Medical Heritage Library. The original may be consulted at the National Library of Medicine (U.S.)
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![[2] function in the cord, and has demonstrated three orders of cells giving origin to different functions, which are as follows: First, the round or oval cellules ; Second, the stellate cells; Third, the fusiform cells. In birds he found the ganglion cells and the cellules of movement largely developed, while those of sensibihty are inconsiderable, [relatively ?] It was also found that the ct-Uulcs of movement in these existed in the posterior comua, and that in this case the elemental arrangement differed from that found in mamifers, for in these latter the afferent elements are largely developed, [exclusively ?] in this part of the organ. The cotemporaneous researches of Lenhossek, do not lead us farther than those of the preceding author, nor so far even, as regards the primordial ele- mental features of these three orders of nervous function. This short resume of our positive knowledge on this subject I have thought not inappropriate, as it furnishes at a glance the important features to be con- sidered in future investigation. It is from this point of view in which Jacubow- itsch has left us, (as we glean from his official report) that we now take our departure, not that any new elements have been developed under our observa- tions, but to localize those elements in such manner that thay may be more readily found by those commencing these investigations, than can now be done by the publications at our command. Without further preface I will proceed to state the results of my observations in relation to these cellules, and their positional relations to one and the other. The spinal cord of the sheep was selected for the experiments about to be detailed, for the reason that the animal holds a comparatively recent origin in the animal kingdom, and among quadrupeds possesses a marked delicacy of structure. The rapidity with which softening of its nervous tissues occur after death, being equalled only by that of man. One of the great obstacles heretofore, has been a want of transparency in sections of nerve tissues, which as a consequence would render very much of the minutiae of detail obscure or absolutely unresolvable; those objections urged against researches of this character are now removed from the fact that our sections are rendered perfectly transparent by subsequent modifications of Stilling's process, recently introduced by J. L. Clarke, of London. Although the white substance of Schwan is rendered so perfectly transparent as to be imperceptible on the stage, still the outline of the cellules of the cord with their nuclei are so well defined that their characteristics, even to tlie minute structure of the cell-wall, is easily seen. The learned owe much to the researches of Mr. Clarke in thus enabling them to obtain such superior defini- tion of these minute forms of structure. I would here state in connection with this part of the subject, that the process of Mr. Clarke is far from complete, and that he will find less color, and better definition, in using the neutral chromate of potassa, and subsequent to this a very dilute solution of caustic alkali; neutralizing the latter with acetic acid, and washing with water; the chemical reasons for this will become apparent to him at once on a moment's reflection. I have thus obtained sections perfectly transparent, and ready for mounting in seventeen hours.](https://iiif.wellcomecollection.org/image/b21160211_0004.jp2/full/800%2C/0/default.jpg)
