The anatomy of the central nervous organs in health and in disease / by Heinrich Obersteiner ; translated, with annotations and additions, from the third German edition, with all the alterations and corrections prepared by the author for the forthcoming fourth German edition by Alex Hill.
- Heinrich Obersteiner
- Date:
- 1900
Licence: In copyright
Credit: The anatomy of the central nervous organs in health and in disease / by Heinrich Obersteiner ; translated, with annotations and additions, from the third German edition, with all the alterations and corrections prepared by the author for the forthcoming fourth German edition by Alex Hill. Source: Wellcome Collection.
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![EMBEDDING IN CELLOIDIN. iis a rule, too brittle to cut. The surface may be partially thawed by touching it with a wet camel’s-hair brush. No microtome is more suitable for cutting frozen nervous tissue than Roy’s; the extremely oblique position of the razor and the circular movement enable one to avoid breaking the section transversely, as is very apt to happen when a knife is driven straight forwards through the extremely friable frozen nervous tissue. The sections are lifted from the razor into salt solution with a large wet camel’s-hair brush.] Properly hardened tissues can be embedded for cutting with the sledge- microtome in pasteboard or metal boxes filled with wax and oil, or, if they are of no great depth, they may even be stuck on a piece of cork. If they arc to be cut on cork they must be placed with the cork in a thick solution of gum, out of which both are lifted together into absolute alcohol in which they remain for twenty-four hours. Better still is the treatment with a thick solution of celloidin, which I give in detail below, as gum is apt to become so hard as to injure the knife. To insure the uniform thickness of the sections, it is almost always necessary to have recourse to the method of embedding, or (more strictly speaking) soaking the preparations in celloidin or pliotoxylin. The solution for this purpose is made by putting small pieces of celloidin into a mixture of equal parts of sulphuric ether and absolute alcohol. The amount of celloidin must be determined by the required thickness of the solution. As celloidin dissolves very slowly (especially after it has once hardened) it is often better to use pliotoxylin, which is entirely dissolved after a few minutes in the same mixture. The preparation must first be completely dehydrated in absolute alcohol (pieces of spinal cord about 1 centimeter thick, taken out of a watery solution, are placed for two or three days in common alcohol, and then for the same length of time in absolute alcohol; larger pieces require a corre- spondingly longer time). They are then put into a very thin solution of celloidin. In this they remain for a variable time according to thickness (three or four days for pieces of the size mentioned). Next they are trans- ferred to a syrupy solution of celloidin, in which they remain a few days at least. After this a piece, now thoroughly saturated, is lifted with the adhering celloidin on to a cork or wooden block, to which it is made fast in the following manner. Its upper surface is painted freely with the thick celloidin or photoxylin solution, and exposed to the air for a while to dry. The preparation—its under surface being made as smooth as possible—is then laid on the cork and again coated with the solution to make it stick more firmly. It is left exposed to the air till the celloidin is almost set, and then cork and preparation together are placed in weak alcohol (70 or 80 per cent.). This is made by mixing the common 95 per cent, alcohol with water in the proportion of about 10 to 12. In twenty-fom’ hours the celloidin will have hardened and be ready for cutting, but pieces stuck upon cork in this manner can safely be left in the weak alcohol for a longer period. If the sections cannot all be cut at one time, it is well to protect the cut surface with a coating of celloidin before putting cork and prepara- tion back into the weak alcohol.](https://iiif.wellcomecollection.org/image/b28716826_0038.jp2/full/800%2C/0/default.jpg)
