ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
565 
the blade of the knife by means of a needle, and arranged in a single 
row until the blade is filled. To remove them a heavy paper spatula 
is placed directly upon the section to which it adheres, and may be 
drawn off the edge of the knife and transferred to the slide. By 
slight pressure, together with a rolling movement, the section is left 
in the desired position. Sufficient alcohol is kept on the slide to 
prevent drying, but not enough to allow the sections to float. When 
the requisite number have been arranged, they are covered with a 
strip of toilet paper which is held on the slide by winding it with 
fine thread. The sections being thus firmly held in position may be 
stained, &c. They should not be placed in absolute alcohol, but 
cleared from 95 per cent, in a mixture of equal parts of bergamot oil, 
cedar oil, and carbolic acid. When cleared the excess of fluid is 
removed by a piece of blotting-paper with gentle pressure, sections 
which are by chance loose are firmly fixed in position, the thread is 
now cut, the strip of paper rolled back, balsam and cover applied. 
If the object can be stained in toto, which is often the case, much 
time may be saved by the following method: The stained object is 
imbedded in the usual manner, but after hardening in chloroform, and 
removing the paper, the celloidin block is transferred to 95 per cent, 
alcohol for twenty dour hours, then to carbolic acid* or glycerin in which 
it becomes as transparent as glass.j The block is fixed in the usual 
manner. 
Orientation is now accomplished with the greatest ease. In cutting, 
the knife is wet with the clearing medinm given above. The sections 
may be arranged in serial order on the knife-blade until a slideful is 
obtained, when they are transferred, balsam and cover applied. By this 
method long series may be readily handled. Glycerin is used only when 
the mounting medium is glycerin. In this case the knife is wet with 
glycerin.” 
Taylor’s Freezing Microtome.J — Dr. T. Taylor remarks : — “ This 
combination microtome is adapted to three methods of section-cutting. 
The instrument is of metal screwed to a block of polished mahogany. 
There is a revolving table with graduated margin, in the centre of which 
is fitted a freezing-box having two projecting tubes, one to admit freezing 
water, the other an outlet for it. The water is supplied from the reservoir 
and carried off by means of rubber tubing which is attached to the metal 
tubes, the terminal end of the outlet tube being furnished with a small 
glass tube, by means of which a too rapid outflow of water is prevented. 
The tubes of the freezing-box are so arranged as to prevent their revolving 
with the revolutions of the table. When ether is used, the little brass 
plug in front of the freezing-box is removed and the rubber tubing 
detached. 
In preparing to make sections, remove the freezing-box, and in its 
place substitute a cork which projects suitably, holding the object from 
which sections are to be taken, imbedded in wax or paraffin, at the 
* Burapus (Am. Nat., Jan. 1892) advises the use of thymol. 
t Since discovering this method of rendering celloidin blocks transparent, which 
was published in the Bot. Gaz., 1890, I have found that the clearing mixture given 
above answers the same purpose as the carbolic acid, but requires a little longer 
time. % Amer. Mon. Micr. Journ., xiii. (1892) pp. 25-6. 
