160 
NOTES AND MEMOEANDA. 
random from the market, but have failed to find a single diatom. 
This to a certain extent surprised me, when taking into consideration 
that they are found to a limited extent in Peruvian guano. The in- 
ference to be drawn is, that the soil was not fertilized by any material 
into which it entered as a constituent. I mention this to guide others 
who may make subsequent investigations from falling into error, in 
case occasional Diatomaceae are observed, as being derived from other 
sources than the infusorial deposits. 
" These microscopic investigations show the absence of other 
forms of silica, that is, in granular particles in the (Kunkel) straw, 
they being entirely replaced by diatoms. This leads to the conclusion 
that the diatom is the more acceptable for assimilation, and when suffi- 
cient infusorial remains are present, replaces any other divided form of 
silica. I have previously attempted to substitute silica for diatoms, 
as obtained from the decomposition of slags from iron furnaces, but 
have failed to derive any satisfactory results. This is due to its com- 
bination as a silicate ; and when liberated by stronger acids, it 
agglutinates into masses too hard and large to be absorbed by the 
plant." 
[We confess that the Plate hardly satisfies our mind. — 
Ed. 'M. M. J.'] 
[Many pages of our " Progress " have had to stand over till 
next number, in order to make room for Dr. Woodward's important 
paper.— Ed. 'M. M. J.] 
NOTES AND MEMOEANDA. 
Salicylic Acid in Microscopy. — On this subject the following note 
appears from the pen of Mr. A. Mead Edwards, in the ' American 
Journal of Microscopy ' (June 1876). He says : — " I have been waiting 
anxiously from day to day to see if some one would not announce the 
fact that in salicylic acid, the marvellous disinfectant and preservative, 
the microscopist had a firm and valuable friend. But as no one has 
said anything as to its value as a preservative of microscopic objects, 
I have felt it my duty to come forward and say my say. Towards the 
end of 1874, as soon as I saw the announcement of the wonderful pro- 
perties of this substance, I tried it in medicine and in microscopy, 
and in both fields found it of inestimable value. I put up some casts 
of uriniferous tubules obtained from a severe case of nephritis, and 
to-day those specimens are in as good a condition as they were the 
day I put them in clear water, with a few grains of salicylic acid 
added. Every medical microscopist, at least, knows how perishable 
casts are, and will, I feel sure, thank me for this hint. Leucorrhoeal 
discharges put up in 1874 do not appear to have changed in the least ; 
and if salicylic acid will preserve such things as these, what will it 
not do ? At present I am experimenting with it on various substances, 
and although it seems to alter the colour of most vegetable tissues, yet 
the softer and more perishable parts are so nicely preserved, that I 
feel that in it the working microscopist has a medium of greater value 
