828 * The American Naturalist. [September, 
with the naked eye the pathologist makes up his mind as to what 
exact parts he desires to submit to microscopic examination. With a 
sharp knife he takes a thin slice of such a part, not more than two to 
four millimetres in thickness and of comparatively small superficial 
area. The piece of tissue is placed in a test-tube containing some 
cotton-wool at the bottom, and half-filled with absolute alcohol. The 
slice is so placed in the tube that it shall lie flat and not be distorted 
or curved. The vessel is now to be placed at a slightly elevated tem- 
perature, for which purpose a water bath is most suitable. I use a 
hand basin, the hot tap of which is left running so as to keep the water 
at a temperature which may be judged of by the hand. The slight 
current in the water is a distinct advantage. If the piece be at all 
bulky it may be well to renew the alcohol after a short interval. In | 
the course of half an hour or three quarters the slice of tissue will | 
generally be found sufficiently hardened to be proceeded with further. : 
2. In the next stage advantage is taken of the fact that anise-oil 
freezes at a comparatively high temperature (45° to 70° Fahr.), and 
—. that the presence of alcohol does not interfere with the process of freez- 
ing. My attention was called to this agent by a paper by Kühne. 
. This author recommends anise-oil as an embedding material, but I 
have not found the method which he recommends very successful. I 
use the anise-oil, not to penetrate the tissue, like celloidin or paraffin, 
but rather to hold it and fix it on the plateof the microtome. Having 
taken the slice of tissue from the alcohol, I dry it with blotting-paper 
or an absorbent cloth. I then pour a few drops of anise-oil on the 
plate of the freezing microtome, and place the piece of tissue in the 
midst of the oil. It is better to have the oil making one convex drop 
with the specimens in the middle of it, asin cutting the sections the less 
- oil you take with you the better. A few systoles of ho ether pex 
bellows suffice to freeze the oil into a white solid mass. The knife 
now used with a considerable sweep, and the section may be cut dry if 
dts superficial area be small. lfthis cannot be done without risk of £3 
-and any microtome with a sliding knife will serve. “Ibis possible, by ; 
. this method, to obtain sections. sufficiently thin for most purposes, 
. although not equal, of course, to those Which tioy, be got alter a em- 
bedding i in celloidin or in paraffine. “a 
.. In regard to the size of the piece of tissue to ie cut, iti is aiy * 
etter: to have it of small dimensions, but the method is. perfectly ap- — 
re plieable to such a piece as would involve, say, the whole Hk of the : 
^ ved ro ds cortex x and dore 
