510 Wager . — The Nucleus of the Yeast- Plant. 
a large proportion of them were lost owing to their loose 
attachment to the cover-glass. The method I adopt obviates 
these difficulties, and in practice it is found that the cells 
may be completely dried up on the cover-glass without 
showing any signs of disintegration, if they have previously 
been well fixed and hardened. The method of procedure 
is a simple one. They are first of all placed in the fixing 
solution, either corrosive sublimate or preferably a solution 
of iodine in potassium iodide. They are then washed * in 
water, 30 °/ o alcohol, 70°/ o alcohol, and finally in methylated 
alcohol, which is constantly changed until all the iodine is 
washed out. Cover-glass preparations may then be made. 
A small quantity of the alcohol with Yeast-cells is placed 
on a cover-glass or slip. The alcohol is allowed to evaporate 
until the cells are nearly dry ; then a drop of water is added 
and the Yeast-cells are thoroughly mixed up in it and spread 
out in a thin layer. When they have settled down the water 
is drained off, and they are then allowed to dry up com- 
pletely. The cover or slip, with its layer of cells, is placed 
in water again for a few seconds and then stained. 
Staining and Mounting. 
Nearly all the methods of staining in vogue for nuclear 
work have been tried with more or less success. 
Fuchsin and methyl-green. This is a very useful combina- 
tion. It is prepared by adding an aqueous solution of 
methyl-green to an aqueous solution of acid fuchsin until 
a deep violet liquid is obtained. A drop of it placed on 
quite damp or wet blotting-paper should show a deep violet 
central spot surrounded by a narrow irregular blue or green 
ring. Cover-glass preparations stained in this for two 
minutes, then washed in water for ten seconds or so and 
mounted in dilute glycerin, show the nuclear body red, the 
cytoplasm blue-pink, and the vacuole and its contents blue, 
nearly the same colour as the protoplasm. The nuclear body 
may be perfectly easily made visible even in the most 
refractory specimens by this method, and especially in the 
