Schäfer’s modification of Pal’s method.—In this method hardening in Müller’s fluid for three or four weeks is sufficient. The sections are made exactly as in the previous method, and transferred to Marchi’s fluid (p. [24]) for six hours. They are washed and stained all night in the following:—
| Hæmatoxylin | 1 | 4 | grs. |
| Alcohol | 10 | 45 | min. |
| Acetic acid (2 per cent. aqueous solution) | 100 | 1 | oz. |
The subsequent processes of differentiation, bleaching, &c., are exactly the same as in Pal’s method.
Osmic acid.—Employed with fresh and also with hardened specimens to demonstrate the medullary sheath. Much the best results are obtained with the former. The nerves, or small pieces of the central nervous system are placed in half to one per cent. solution of osmic acid as soon as possible after death and kept in the dark for about a week. The tissue must be very thoroughly washed in running water to remove all traces of osmic acid, and then stained for a couple of days in borax carmine to demonstrate the nuclei and axis cylinders. Sections may be made in gum, or the tissue may be teased with needles and then mounted in Farrant. Embedding in celloidin, and mounting in balsam are inadvisable, because the ether tends to dissolve out myelin, and the clarifying oil to render it too transparent.
2. Intra-muscular ramifications of nerves:—
Sihler’s chloral hæmatoxyline method.—This method reveals the intra-muscular nerve-endings, and also brings into prominence the curious “muscle spindles” which Sherrington has shown to be connected with the posterior nerve roots, and which are believed by some to be the end organs subserving muscular sense.
A piece of muscle is taken as soon as possible after death, or from an amputated limb, and slices cut about one-tenth of an inch thick with the freezing microtome. Transfer for twenty-four hours to the following solution:—
| Acetic acid | 1 | part. |
| Glycerine | 1 | " |
| One per cent. aqueous solution of chloral hydrate | 6 | parts. |
The tissues swell up in this fluid and become translucent and gelatinous in appearance. They are now placed in pure glycerine until saturated as shown by their sinking to the bottom of the dish. This usually takes several days. They may now be stained in the following solution:—
| Ehrlich’s hæmatoxyline (p. [70]) | 1 | part. |
| Glycerine | 1 | " |
| One per cent. aqueous solution of chloral hydrate | 6 | parts. |