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quent examination. One of these methods is extremely easy 
and quick in its action, and although the penetration into larger 
lungi may have to be facilitated by puncturing, slashing, or 
cutting the specimen if it is intended for histological examin- 
ation, | have obtained excellent results with it for museum pur- 
poses by merely plunging a Boletus or Agaric into the medium 
as a whole. 
The hardening and fixing fluid is prepared by adding a few 
drops of concentrated acetic acid to a solution of corrosive 
sublimate in water, and allowing the specimen to soak in this 
for 24 hours or more, after which it may be bottled in alcohol 
without more ado.* The corrosive sublimate—mercuric chloride, 
HgCl,—is, I need hardly remind you, a dangerous poison, but it 
has the advantage of being easily carried in crystals and made up 
as required. 
Small fleshy fungi, such as species of Mycena, Coprinus, 
Leotia, &c., and gelatinous forms, such as Exidia, Auricularia, 
&c., as well as delicate moulds like Mucor, Pilobolus or parasites 
like Saprolegnia, Peronospora, Cystopus, &c., can be beautifully 
fixed and preserved by this means. 
If you want the best attainable results, however, in the way of 
perfect fixation and hardening for histological purposes, I would 
recommend the following much more troublesome method, the 
principal drawbacks to which are, that it is extremely difficult to 
carry out the very thorough washing process (absolutely 
necessary for success) when travelling or away from the labora- 
tory, and that the solutions and alcohols are so much more com- 
plex. 
The specimens—whole or in pieces according to their size and 
consistency—are plunged fresh into weak Flemming’s solution for 
12-24 hours or even longer. They are then washed in running 
water for at least the same period, until every trace of the fixing 
fluid is removed, and then transferred to the following in succes- 
sion, in each of which the specimens should remain for 12-24 
hours—viz., 30 per cent., 50 per cent., 70 per cent., and go per 
cent. alcohol. Here they may remain for transmission or for 
further treatment to be referred to subsequently. 
For some purposes it will be regarded as a disadvantage that 
the osmic acid in the Flemming’s solutiont stains the objects black, 
* A good formula is that of Keiser’s solution— 
Hg Cl, =5 grams. 
Water = 300 c.c. 
Acetic Acid=3 grams. ([See, for instance, Strasburger Das 
Botanische Practicum, 3rd ed., p. 50. ] 
TA suitable solution is :— 
Chromic Acid 0°25 per cent. 
Osmic Acid O'l 6 
Acetic Acid ol ¥ 
Water 99°73 
(See Strasburger 1. c. or any of the histological 
manuals. ) 
