i88i.] 
Notes. 
Dr. M. C. Cooke, in calling the attention of the Quekett Club 
to some Desmids new to Britain, gives an account of the best 
method of preserving them permanently for microscopical ob- 
servation. The most important objetft to be secured in mounting 
Desmids is rather the preservation of the empty frond, as for 
scientific purposes this is often of superior value to one filled 
with endochrome, as it permits the punctce or markings of the 
segments to be seen, which are obliterated whilst the endochrome 
remains. For the study of the endochrome alone of course its 
presence is most important ; but this can be done, and drawings 
made from the plant in the living state, and if specimens can be 
mounted with the endochrome unchanged and uncontrasted so 
much the better. One great difficulty in mounting objedts with 
such thin and delicate cell-walls as Desmids is to employ a 
medium of no greater density than the cell contents. If a denser 
medium, such as glycerin, be used, the endochrome immediately 
contracts, and never expands again as before. Water, or water 
containing a little camphor, is of equal density, and no change 
can be detected. After all, the preservation of the endochrome 
is of less importance than the perfect contour of the cell. If 
there is any contraction or collapse the objedts are useless. 
Supposing, therefore, that there is no necessity to preserve the 
endochrome, there is another feature to remember besides the 
preservation of contour, and that is, that the medium employed 
should not render the delicate cell-walls so transparent as to be- 
come ultimately invisible. In simple water Dr. Cooke found no 
difficulty in discerning the structure of the cell-walls after a 
period of not less than twelve years. So much cannot be said 
for glycerin. As a hint it may be added that empty fronds, both 
of Desmids and Volvox, stained of various colours, exhibit all 
the details in an unexceptionable manner. 
Some time ago we ventured to predict that not even the total 
suppression of vivisection would satisfy the hysterical party. 
Our words are being fulfilled. It is voted cruelty to feed snakes 
with live rabbits, &c., and as they will not, as a rule, touch dead 
food, English naturalists will have to go abroad if they wish to 
study serpent life. 
Lest the chemists should laugh at the biologists, it is proposed 
that the three chief mineral acids — the sulphuric, nitric, and hy- 
drochloric - should be placed on the list of poisons, and their 
sale encumbered with red-tape precautions. This idea, if carried 
out, will no doubt wonderfully facilitate chemical research in 
England. 
M. Pasteur has received the gold medal of the French Society 
of Agriculturists for his researches on fermentation and con- 
tagion. 
The “ Scottish Naturalist ” for April contains the first portion 
