THE MICROTOMIST' S VADE-MECUM

recent writer (A. C. Cole, in " Methods of Micr. Research," vii,  jeopt
1884, p. 41, cf. 'Journ. Roy. Mic. Soc.' (N.S.), 1884, p. 310) that T1
" no stain has been found to equal logwood for certainty and
permanence of results," but he affirms also, that this perma-     1
nence is only obtained with benzol-balsain mounts. Flemmingl Or, a
finds humatoxylin stains lose in sharpness after about a year,      t t
both in glycerin and in resinous media (Flemming does not        ot estal
state which resinous media he means, but it is probable he
refers to dammar). Other writers assert the stain to be per-
manent both in glycerin and in dammar, provided certain          but se
precautions be taken, for which see Nos. 92 and 93.
We do not yet possess sufficient data to enable us to judge     P"
surely  of the permanence of anilin stains.        Flemming,       Cock
writing in 1882 (1. c., p. 384) states that of all his preparations  e
safranin  and napthalin (dammar mounts) have kept the             tolh
best, showing no change whatever since 1878. Chromic acid
gentian-blue stains fade a little in the course of a year, but
not so much as the hmematoxylin stains.        It is certainly     o
premature to condemn anilin stains en bloc for a want of Itsk
permanence that has not been proved against them.
The same writer (Cole) appears to assert that picro-carmine     kLA
stains keep better in glycerin jelly than in any other medium;     Pe
he says that " a preparation stained with picro-carminate of        l
ammonia and mounted in good glycerin jelly is unchange- th
able." Doubtless picro-carmine stains are well preserved in 5
glycerin jelly, but so they are in all the usual media; in thS
acidulated glycerin (formic acid glycerin) they are still E
better preserved; and in dammar, balsam, or colophonium            ih a
they, in common with other carmine stains, keep perfectly.
And as for the unchangeableness of glycerin-jelly prepara- ime
tions, does Mr. Cole, who asserts that they "would last a           id
thousand years, and be as perfect the last day as on the first," thti
really mean such statements to be taken seriously? h
The greatest difficulty in the technic of staining lies in the   am11
1 'Zellsubstanz,' p. 384.                       I
.........

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