752 General Notes. | October, 
PERMANENT Microscopic PREPARATIONS OF AMPHIBIAN BLOOD. 
—The very excellent method of drying the corpuscles of mam- 
malian blood on the microscopic slide, is not applicable to the 
much more bulky corpuscles of Amphibia. The corpuscles of 
the latter are sure to be distorted and seamed in drying; hence 
various methods of preserving the corpuscles moist have been 
tried with varying success. 
The following very great modification of the method proposed 
by Ranvier in his treatise on histology,' has been in use for some 
time in the Anatomical Laboratory of Cornell University, and 
has given uniformly excellent results. Preparations made three 
years ago are quite as good as at first. 
Three or.four drops of fresh blood are allowed to fall into 10 
cc, of normal salt solution (common salt 750 milligrams, water 
100 cc.) preferably contained in a high narrow vessel like a 
graduate glass or beaker. The mixture of blood and salt solu- 
aqueous solution of picric acid added with constant stirring. 
After the corpuscles have settled, as much of the supernatant 
liquid as possible is poured off, and in its place is put about an 
equal volume of normal salt solution. The corpuscles are 
allowed to settle, the liquid poured off and another volume of 
d -ibis 3 
salt solution added, >This is continued until the salt solution 
acquires only a faint yellow tinge. 
The use of the salt solution is, first, to dilute the blood in 
order to avoid distortion of the corpuscles, and second, to wash 
away the picric acid so that the subsequent staining will be more 
satisfactory. 
After pouring off the last salt solution, there is put in its place 
.10 cc, of a mixture of five parts of Frey’s carmine and ninety- 
five parts of picrocarmine. The corpuscles will stain in from one to 
fifteen hours. drop of the agitated mixture should be exam- 
ined occasionally to ascertain when the staining is sufficient. The | 
nucleus should be deep red, and the body of the corpuscle yel- 
low or pinkish. ; 
en the staining is completed, as much stainer as possible 
should be poured off, and in its place 10 or 15 cc. of acid glyc- 
erine (glycerine 100 cc., acetic or formic acid I cc.). This mix- 
re of corpuscles and glycerine may be placed in a bottle and 
used at any time, it being simply necessary to agitate the 
mixture slightly or to take up some of the sediment with a 
pipette and mount it precisely as any other glycerine preparation. 
Summary—ı. The fresh blood is first diluted with about fifty 
times its volume of normal salt solution. ` 
2. To this diluted'bldod is added ten times as great a volume 
of a saturated aqueous solution of picric aci 
acid. ; 
3. The picric acid is washed away with normal salt solution. 
1 Traité technique de Histologie; p. 195. 
