Microscopy. 379 
MICROSCOPY.! 
A New METHOD FOR THE MicroscopicaL STUDY OF THE 
Buioop.*—The methods hitherto employed in preparing the blood 
for microscopical examination have aimed either at the production 
of fresh or of dry preparations. Preparations of the first class are 
not permanent, and those of the second class never exhibit the mor- 
phological elements intact. Dr. Biondi has worked out a method 
which combines the advantages, and is free from the defects, of 
previous methods. The problem was to find the means of perfect 
ation, preservation, imbedding, and mounting—in other words, a 
method by which the blood could be treated as a solid tissue. The 
method is equally useful in the study of other organic fluids, and 
has been successfully employed in tracing the changes that take 
place in the maturation of the spermatozoa. It may doubtless be 
sity advantage in the study of Infusoria, as suggested by 
iondi. 
The point of chief interest in Biondi’s method is the use of agar 
as an imbedding material. Agar is a vegetable gelatine, obtained 
from Gracilaria lichenoides and Gigartina speciosa, and has already 
been successfully employed for some time by Koch in bacteriologi- 
cal investigations. Among the different sorts of agar, the colum- 
nar form Saulen-Agar) is considered the best. A perfectly trans- 
parent solution is required, in the preparation of which great care 
must be taken. This may be accomplished in the following man- 
ner: Place two parts of agar in 100 parts of distilled water, leav- 
ing 1t to soften for twenty-four hours at the ordinary room temper- 
ature ; then heat to boiling on the sand-bath until the agar is all 
dissolved. The evaporation of the water may be checked by clos- 
ing the flask with a cork provided with a long glass tube. Add 
carbonate of sodium to the point of weak alkaline reaction, and 
for an hour in a steam-apparatus. Pour the solution into 
long, slender test-tubes, and leave from twelve to twenty-four 
ours at a temperature of 50° to 60°C. The solution separates 
into two layers, the upper of which is quite clear, and this layer 
alone can be used for imbedding purposes. But clarification must 
be carried still farther before it is fit for use. The clear put 
egg added, the mixture shaken up several times in the course of 
ten minutes, boiled for an hour in the steam-apparatus, and then 7 
Bi D. Biondi. Neue Methode der mikroskopischen Untersuchung des 
utes. Arch. f. mik. Anat., xxxi., 1, p. 103, Dec., 1887. 
