59 
half that time. In order to stain the nerves, the exposure 
should be longer than for the connective-tissue-corpuscles. 
After some practice, the proper straw-yellow colour of the 
tissue is readily recognised. 
Tails of Tadpoles—A very fine network of nerves, first 
described by Dr. Klein, may be obtained by staining the tails 
of tadpoles with gold in the same manner as the cornea. 
When the tail has assumed the proper tint, it must be placed 
in absolute alcohol, with a few drops of acetic acid in it, for 
about five minutes, when the skin of the two surfaces of the 
tail can be separated from one another, by tearing, with for- 
ceps, from above downwards. Half may then be mounted 
in glycerine. 
In conclusion, it must be borne in mind, that in prepara- 
tion with both gold and silver, constant failures occur, par- 
ticularly when these reagents are used for the first few times. 
That, however, they are worth trying, will be at once con- 
fessed by any one who has seen a good silver preparation of 
the central tendon of the diaphragm of the rabbit, and a 
good gold preparation of the cornea of the common frog, 
showing both the nerves and corpuscles. Moreover, these 
methods are, of course, applicable in many other lines of 
research, these special cases being chosen for description 
only because the writer has paid most attention to them. 
The great thing to remember is, that the tissues used in these 
preparations must be absolutely fresh, in fact, living. 
Dammar-lac.—It may not be out of place to mention here 
an unfortunate error which has crept into the translation 
of ‘Stricker’s Handbook,’ published by the Sydenham 
Society. The word, ‘ Dammar-firniss,” has been translated, 
“Canada balsam.” Dammar varnish is recommended by 
Stricker in his work for mounting histological preparations. 
it is always used in his laboratory, and in those of Bracke 
and Rokitansky, and has there entirely supplanted Canada 
balsam. 
Well-made Dammar varnish has many advantages over 
Canada balsam. It is clearer, more free from colour, and 
when used cold, as it always is, it dries quicker, though it is 
much thinner and more limpid. It is to be hoped that this 
mistake will be corrected in a future edition, as any one who 
has used really good Dammar varnish for histological pur- 
poses will not be likely to try Canada balsam again. 
I have not been able to obtain, as yet, any good Dammar 
varnish in London, though the Gum Dammar is, of course, 
common enough. I have, however, given a sample of Vienna 
varnish to Messrs. Baker, of Holborn, who have promised 
to procure it as soon as possible. 
