NOTES AND MEMORANDA. 161 
piece was used and amplified, still I had oceans of spare light, nor was 
the definition of the objective at all taxed. These results, it seems to 
me, are valuable, in that we can now get rid of the cupro-ammonia 
cell, and of the blue glass: neither of these could be successfully used 
receiving the solar beam through a closed window. With the Wenham 
illuminator I could discover no sensible difference in the definition, 
whether the window was open or closed. This alone, in the winter 
season, will be a great boon to the microscopist.” * 
Cleaning Diatoms with Glycerine.—The ‘ American Naturalist’ 
(February 1877) says that Mr. James Neil, of Cleveland, uses gly- 
cerine as an easy and efficacious means of separating diatom shells 
from the foreign matter with which they are naturally mixed. He 
fills a 2-ounce graduated measuring glass three-quarters full of 
glycerine and water mixed in equal parts. The diatoms, after being 
treated with acid and thoroughly washed, are then shaken up in some 
pure water and poured gently over the diluted glycerine. If care- 
fully done the water and diatoms do not at first sink into the glyce- 
rine, but gradually the diatoms sink through the water, and into the 
glycerine, preceding the light flocculent matter held in the water. 
After a few minutes, a pipe introduced closed through the water and 
into the glycerine will bring up remarkably clean diatoms, which are 
to be afterward freed from glycerine by repeated washing and 
decanting. 
Eosin: a New Staining Fluid.—Dr. Dreschfeld states in the 
‘Journal of Anatomy’ (vol. xi. part 2) that a solution of eosin, of 
1 part to 1000 of water, forms an admirable staining fluid. The 
sections to be stained, having been immersed in this fluid for one 
minute to a minute and a half, are put for a very short time into 
water slightly acidulated with acetic acid, and can then be mounted 
in glycerine or in Canada balsam. The advantages claimed for this 
fluid by the author are these:—1. The time required for perfect 
staining does not exceed one to one and a half minute. 2. The solu- 
tion can be kept without altering, and remains perfectly clear for any 
length of time. 38. Hosin has the property (probably owing to its 
fluorescence) of clearing tissues. 4. It differentiates the component 
parts of a tissue, which renders it particularly applicable to com- 
plicated structures, as tumours. Dr. Dreschfeld finds it particularly 
useful in the examination of nervous tissue. The nuclei, nucleoli, 
and processes of the ganglion-cells, and the axis-cylinder of nerve- 
fibres, are stained light pink; the areolar tissue takes a much deeper 
colour; the medulla of the nerve-fibres, on the other hand, is not 
stained at all. 
* See ‘ Cincinnati Medical News,’ January 1877. 
