1887] Microscopy. 595. 
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tion requires also acquired ideas, the field of controversy between 
the intuitional and experiential theories is narrowed to these 
. ment of the proposition; but without evolution by experience, 
man would never have acquired the power necessary to do this. 
—E. D. Cope. 
MICROSCOPY.: 
O. Schultze’s Method of preparing the Amphibian Egg.2— 
For hardening-fluids the following mixtures were found to give 
perfectly satisfactory preparations, when used in the manner 
described below : 
1. Chrom-osmio-acetic Acid. 
Chromic acid (1%) 25 parts. 
Osmic si a A Io “ 
Water. ; mi 
Acetic acid (2%) 5“ 
2. Chrom-acetic Acid. 
Chromic acid (1%) 25 
Acetic " (2 si ) ‘ec 
Water. "QO «6 
The eggs are left in one of these fluids twenty-four hours, 
then washed in distilled water, which should be often changed. 
The egg-envelopes are next removed by the aid of needles, and 
the eggs are then ready for surface-study, 
For the purpose of sectioning the eggs are transferred from 
the water used in washing to 50% alcohol, then to 70%, 85%, 
and 95 %, leaving them twenty-four hours in each grade. The 
last grade should be changed several times. The eggs are then 
ified in turpentine one to two hours, and then placed in par- 
affine that melts at 50° C. for one-half to one hour. 
* Edited by C. O. WHITMAN, Ph.D., Milwaukee, Wisconsin. 
2 O. Schultze, Zeitschr. f. wiss. Zool., xlv., H. 2, p. 185, April, 1887. 
