170 
obtained, than in any other domain of science that has had the 
misfortune to become the hobby of the dilettante, not even ex. 
cepting the collecting of dried plants. Personally, | am strongly 
in favour of eliminating all but one or two well tried methods 
of staining capable of very general application, and in the pre- 
sent instance shall confine myself to two only, which I have 
myself found to be extremely valuable. 
There are several methods of hardening and staining the more 
delicate fungi for the purpose of permanent microscopical pre- 
paration, of which we may select the following as one which has 
been found generally useful. 
Suppose we have a satisfactory growth of such a form as a 
Saprolegnia, growing on a fly floating in water, or of a 
Mucor developed on a piece of fruit, bread, &c. In such cases 
the whole mass may be thrown into the weak Flemming’s solution 
and be killed, fixed, and hardened in one operation, the washing 
and passage through the alcohol being very thoroughly and care- 
fully accomplished as before. 
The material having reached the last stage of hardening, in 
absolute alcohol, is then placed bodily into a dilute solution of 
iron-alum, and left there for several hours until thoroughly pene- 
trated by this re-agent. 
This done, the fungus is transferred to water for a few seconds, 
to remove the adhering excess of alum, and then cast into a very 
dilute staining fluid made up in various ways, of which the 
following extremely simple one is perhaps as good as any :—5 
grams of Haematoxylin dissolved in a litre of distilled water. 
Almost any desired depth of staining can be obtained by this 
solution, if attention is paid to the thorough washing out of the 
iron-alum, bleaching by means of hydrogen peroxide if necessary, 
or partially decolourising by re-immersion in iron-alum, and so 
on.* 
The properly stained fungus is now passed again gradually 
through the alcohols, to prevent contraction when transferred 
finally to xylol and Canada balsam, or to glycerine and glycerine 
jelly for final mounting. 
Let us now suppose that we have to deal with large fungi, of 
with parasitic forms, such as Puccinia, Aicidium, &c., in leaves 
or other parts, which are too opaque and bulky to mount whole, 
and which must be examined by means of sections. 
Again there are various methods which may be employed or 
modified in different cases, and again we will select one which 
I know from extensive practical experience to be generally use- 
ful. 
*For further details as to these processes the reader is referred to handbooks 
on histology, such as those already cited, or Chamberlain J/e/hods in Plant 
Histology, Chicago, 19gor. 
