1885.] Microscopy. 331 
face preparations. The achromatic spindles are seen to best advan- 
tage in the renal tissue 
Preparation.—a. Place small fresh pieces of the object in chrom- 
Jormic acid (200 g. of a one-third per cent solution of chromic + 
four to five drops of strong formic acid) twelve to twenty-four hours, 
6. Wash thoroughly and harden slowly, first twenty-four to 
thirty-six hours in sixty to seventy per cent alcohol, then in abso- 
lute alcohol.! 
c. Stain in either of the three following wa 
1. Grenacher’s hematoxylin (strongly diluted with distilled 
water) twenty-four hours, followed, after washing, with acidulated 
eg (few drops o 
2. Pfitzner’s safranin two to four hours, followed by absolute 
alcohol, in which the object is ga until no visible cloud of color 
remains upon turning it over F imd about two minutes), clove 
oil a few minutes and dam 
3- Double-stain with Kitistotrlik and safranin; stain very 
feebly with the hæmatoxylin ; wash and treat sao acidulated 
alcohol, and then stain with safranin as in number 
Examination. —High powers are required in he. study of the 
mounted ERRA. either the homogeneous immersion ys of 
Zeiss, with Abbe’s condenser, or that of Hartnack, No. m1, zs 
Nachet’s camera was employed in drawing. 
It it well to work with green light, which can be obtained by 
inserting a pee colored glass plate beneath the table of the 
Microscope, as was first recommended by Engelmann. 
The slide devieed ide Rabl enables one to examine a prepara- 
the tion -otherwise ‘remaining e nie Ctl 
Erea rally feecaes ¢ 
which brings out very di 
spherules of oa ey 
