ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
C07 
flask in connection with the water supply serves to keep the constant 
air-pressure necessary for the injection. A manometer, tube and 
apparatus for stopping air-bubbles must be inserted between the in- 
jection flask and the tube. Since the preserving fluid coagulates the 
blood, the latter must first be washed away by means of physiological 
salt solution. The fixing fluid is then introduced. The injection is 
continued until all visible parts show the change of colour resulting 
from the effect of the fixing fluid. This is then expelled by water, the 
vascular system thoroughly rinsed with alcohol, and finally the whole 
specimen is immersed in alcohol. 
Fish treated in the above way exhibit for preparations the following 
advantages : — 
(1) The preservation is perfectly uniform and allows of an exact 
histological investigation for any given part. 
(2) The firmness of the tissue is perfect. 
(3) By the removal of the blood the injurious saturation of the 
tissues with coloured matter of the blood is avoided, and the pure colour 
resulting from the fixing fluid is obtained. 
Mounting Small Objects in Aqueous Media.*' — Berr H. Reichelt 
says that well-dried pollen-grains, fern-seeds, fungus-spores, &c., may 
be mounted in aqueous media by means of the following procedure. A 
cover-glass is coated with a thin layer of shellac by just dropping on it 
some isobutyl alcoholic solution of shellac and allowing it to dry. 
Upon this film the objects to be mounted are arranged in any manner 
desired, and then the cover-glass is carefully removed to a space filled 
with alcohol vapour. For this an ordinary bell-jar or exsiccator answers 
very well ; a few drops of alcohol are poured on the bottom and the 
preparation placed on a tripod or some convenient vessel. In a few 
hours the shellac layer will have softened sufficiently to fix the objects 
to be mounted, and on removal from the alcoholic atmosphere the shellac 
becomes quite firm again, so that the objects remain in their position 
while being mounted in watery media. 
Study of the Lymphatics of the Mammary Gland, j — M. C. Regaud 
finds that the methods of investigation used by his predecessors are 
sufficient to explain the divergent results at which they have arrived. 
He concludes that it is of great importance to preserve the impregnated 
vessels in a state of distension, but under the influence of strong alcohol, 
which is generally used to fix pieces treated with silver injection, the 
impregnated canals empty themselves and contract. The author’s pro- 
fessor, M. Renaut, has devised a method which avoids this contraction. 
He mixes the silver solution with picro-osmic acid, and makes injections 
with this mixture. The picric acid is to be employed in a saturated 
watery solution. It aids in fixing the tissues, and the yellow tinge 
which it gives to them allows the investigator to judge of the diffusion 
of the injected liquid. The osmic acid may be from 1 in 300 to 1 in 
1000 parts. The nitrate of silver should be a weak solution only, that 
is, 1 in 400 or 1 in 500. The mixture of these three fluids when dis- 
solved in distilled water leaves no precipitate, and may be preserved for 
* Zeitschr. f. angewandte Mikroskopie, i. (1895) pp. 11-2. 
t Journ. Anat. et Physiol., xxx. (1894) pp. 719-24. 
