Freparing and Staining Fresh Brain, &g. By Bevan Leivis. 107 
and a small portion of the medulla are now to be made by the 
same sweeping cuts, the preoaution being observed of keeping the 
surface operated upon as well as the blade thoroughly and constantly 
moistened with spirit. Extremely delicate sections may thus be made 
after a little practice by rapid steady strokes of the knives, and all 
tearing avoided by the floating up of the section upon the moist- 
ened blade. I usually operate upon half-a-dozen sections simul- 
taneously, as no further trouble is involved in preparing a large than 
a small number of such specimens. Having therefore the slides 
well polished placed before us, the finest and more delicate sections 
are selected and placed on the glass slips and a few large drops of 
Miiller's fluid dropped over each section from a glass pipette or 
camel-hair brush. This fluid is allowed to thoroughly deluge the 
section above and below for some seconds, and a circular cover-glass 
dropped on in such a position that the section occupies about one- 
third to one-half the diameter of the cover. The covering glasses 
most serviceable for slides measuring 3 by 1 should be quite 2 centi- 
meters in diameter. The blade of a knife or point of a strong mounted 
needle may next be placed on the centre of the cover and by steady 
gentle pressure the grey matter is flattened out into a thin almost 
transparent film. Practice soon enables the operator to so adjust 
the position of the cover that the extreme edge of this film still 
occupies the space covered by the circle. It will, however, be found 
of very slight disadvantage should the film be partly pressed outside 
the cover-glass, although I generally avoid such an occurrence, as it is 
not so likely to lead to the production of a film of uniform thickness. 
The superfluous fluid is removed by rapid rinsing in water, and the 
slide next transferred to methylated spirits. For this purpose I 
use a flat porcelain bath such as is employed by photographers, and 
which should contain sufiicient spirit to cover the slides. In from 
thirty to forty seconds the film will be found in the best condition 
for removal without tearing. For this purpose the slide is removed, 
one edge of the cover-glass steadied with the finger, and the blade 
of a penknife gradually inserted beneath the opposite edge, and it 
will be found most advantageous to elevate that edge which im- 
pinges on the lower cortical layers or on the medullary substance. 
The cover is in this way most readily removed, and the most perfect 
films remain either loosely floating on the glass slip or closely and 
smoothly adherent to the cover. For rapid staining it is now 
advisable to remove all traces of spirit, and this is most readily 
accomplished by slightly inclining the slide or the cover to which 
the film is attached and allowing a gentle stream of water to flow 
from a large camel-hair brush over it. Having passed through 
this preparatory stage the film is ready for the second stage, that 
of staining. 
Second Stage, — The film is now to be subjected to the agency 
I 2 
