Wager.— The Nucleus of the Yeast-Plant . 509 
acid, and osmic acid alone ; all of which give fairly good 
preparations: but the best results have been obtained by 
a saturated solution of corrosive sublimate, which should act 
for at least twelve hours, and by Gram’s solution of iodine, 
which was used by Moeller, and subsequently by other 
observers, and which I have found to be of immense value 
in this work. The solution should remain on the Yeast 
for twenty-four hours. 
The Yeast-cells maybe fixed en masse in a small bottle, 
or cover-glass preparations may be made. Lindner (’9?) 
observed that Yeast-cells behave in the same manner towards 
dyes as do Bacteria : like them they may be dried on 
a cover-glass and stained with various aniline-dyes. The 
spores also behave in a similar manner to the resting 
spores of Bacteria, and may be stained very easily with 
fuchsin. 
It has been found by Janssens and Leblanc, and by myself, 
that completely drying up the living Yeast-cells on a cover- 
glass produces much contraction and disintegration of the 
contents. Janssens and Leblanc have found, nevertheless, 
that the liquid on the cover-glass may be almost completely 
evaporated without the Yeast-cells becoming quite dry, and 
that they stick sufficiently firmly to the cover-glass to allow 
the subsequent operations of hardening and staining to be 
carried out. 
The method of fixing cover-glass preparations by heat, 
as practised by some observers, is not a good one, as has 
been already pointed out by others, but I should not say 
with Janssens and Leblanc that it is absolument condamnable. 
I have found it useful in certain cases, and have occasionally 
obtained very good preparations. 
The method employed by me, however, is different from 
either of these. I first fix and harden the cells before making 
cover-glass preparations of them. I found that, even with 
the partial drying up, as practised by Janssens and Leblanc, 
the Yeast-cells showed signs of contraction of their contents ; 
and further, that in the process of hardening and staining, 
