1883.) Microscopy. 457 
added to the sea-water, gives the desired results. The alge re- 
main in the solution 4-1 minute, and are then transferred di- 
rectly into 50 per ct. alcohol. 
A new METHOD oF PRESERVING AND STAINING PROTOZOA.— 
For preserving these small organisms, various re-agents have been 
recommended. Certes! and Landsberg” employ osmic acid ; Kor- 
schelt chromic acid or osmic acid ; and Entz,‘ Kleinenberg’s picro- 
ulphuric acid. 
Finally, Blancë recommends the following very dilute picro- 
sulphuric solution :— 
ean 
 Pictic acid (saturated solution in dist. water)........ ae beeterey 100 vol. 
Sulphuric acid (concentrated)........ FA BOL. 
Distilled water 600 vol 
POCO ee ee twee eee eee ewe eee ee eeeeseseeer eee ee eeees 
for 15 grams of the solution. The acetic acid is added in order to 
sharpen the outlines of the nuclei and nucleoli. 
Bick. This liquid is preferable to osmic acid, because it does not 
D render the objects non-receptive to staining fluids. 
. ‘neentire process of hardening, washing, staining and mount- 
mg can be more expeditiously performed under the cover-glass 
no otherwise. The acid is allowed to work until the objects 
gave become thoroughly yellow. The acid is then replaced by 
: ct. alcohol, frequently renewed until the yellow, color 
disappears: 96 per ct. alcohol is next used, and then 
ardened objects may be stained with picro-carmine, or, 
f, With an alcoholic solution of safranin. Five grams of 
Pe dissolved in i5 grams of absolute alcohol; the solution 
nding a few days, then filtered and diluted with half its 
solution of safranin is preferable to picro-carmine, because 
more quickly, and because one can so regulate its action 
a sharp definition to the protoplasm or the nucleus. 
the end 
1S renewed until a moment arrives when no visible clouds. 
° appear; at this moment the 80 per ct. alcohol is 
1 absolute alcohol, and this by clove oil. : 
is soluble in alcohol, the process of washing will of 
Rend. Acad, Sc., Paris, t. 88. 
