8360  . The American Naturalist. [September, 
* 
, 
All the operations described above were conducted in diffuse day- 
light and the gold chloride solution was exposed to sunlight for some 
time before using. This may not be an essential factor to the process, 
but Dr. L. Lindsay Johnson, in the third edition of Lee's Vade 
Mecum, suggests that failure to’ ripen the solution by sunning may be 
the cause of many of the failures in gold staining. 
| C. L. BRISTOL. 
University of Chicago, April 14, 1894. 
Gold Chloride-Formic Acid Staining of Sections after 
Fixation in Sublimate Alcohol.—S. Apathy in the the Zeitschrift, 
für Wissenschaftliche Mikroskopie. Bd. X, 1893, p. 348. 
The following method i is extracted from an article on the muscle 
fibres of Ascaris. - 
_ Take equal parts of a saturated solution of corrosive sublimate in a ` 
a 3 per cent solution of common salt and absolute alcohol ; or dissolve 3 
| per cent of corrosive sublimate and 3 per cent common salt in 50 per 
-eent alcohol. Use the liquid boiling hot for Ascaris, cold for leeches, 
and leave the animals i in it for 24 pours, or at least 12 hours. Wash 
out in 50 pe l untilt y-brown color of an iodine- 
* aleohol | solution. remains Quee for a few days. Free the tissues | 
-Imbed in paraffin, using chloroform 
for the transferring. medium, and fix the sections on the slide. Free 
. them completely from paraffine and chloroform, and finally : wash 
— Slightly with distilled water. 
Put the slide in a 1 per cent gold chloride solution and keep i in the. 
dark for 24 hours. Drain the slide and lightly apply a smooth-faced ` 
blotting paper to take up the surplus liquid. A yy percent solution — — 
of gold chloride will answer, and is, of course, cheaper. Without Dt 
further washing put the slide i in a large bulk of 1 per cent formic — 
x E and leave it for 24 hours. The longer diffuse daylight acts on - 
the sections, the better the results. Wash. in distilled water and | 
mount in balsam. The sections may be cut very thin or thick—from | 
ol ^, but the author mma oue best results from. sections. 2 or 2i 
"d eie T 
"By thie simple p em ced i jb i foo «edi Wu dees d 
produced the most beautiful pietures of the crores of various | 
tissues, but especially muscle and nerve. fibres. - ‘he various elements : 
paid honest in different tints from rose to cherry red or 
