Wager —The Nucleus of the Yeast-Plant. 513 
carmine very thoroughly as well as the nigrosin. A long 
stay in the alcoholic solution of acetic acid is generally 
necessary. This method is best adapted to the staining of 
cells which are to be cut by the microtome. I have also been 
able to obtain useful preparations showing the division of the 
nucleus in spore-formation by means of it. 
Regina-violet. An aqueous solution is used. The cells are 
stained for about two minutes, then washed in water and 
50 °/ o of alcohol, and mounted in dilute glycerin. Nuclear 
body, vacuole, and protoplasm stain reddish, but the nuclear 
body and vacuole are differentiated from the cytoplasm by 
being rather more deeply stained. 
Microtome-sections. 
The fixed and hardened Yeast-cells may be stained, 
according to the method of Hartog, in carmine and nigrosin. 
The methylated spirit in which they are preserved is poured 
off and replaced by a very dilute solution of acetic acid 
nigrosin in 50 °/ o spirit. After remaining in this a short time, 
the liquid is drawn off and replaced by Mayer’s carmine ; the 
liquid is well shaken and allowed to remain for several hours. 
The carmine is then poured off, and the Yeast-cells are 
washed several times in 30 °/ o alcohol, which is then replaced 
by acetic nigrosin in very dilute solution. They should 
remain in this until sufficiently differentiated, which may be 
ascertained by occasionally placing a few cells under the 
microscope. When this has taken place the stain is drawn 
off, 30 °/ o alcohol added, then 50 °/ o , and they are gradually 
brought into absolute alcohol, in which they remain for an 
hour or so. The absolute alcohol is replaced by carbolized 
xylol, and the bottle or tube containing the stained cells is 
then placed on a water-bath, and pieces of hard paraffin wax 
added until all the xylol is evaporated and the cells are left in 
pure paraffin. They are then well shaken to ensure thorough 
penetration, and allowed to settle in a mass at the bottom of 
the tube or bottle. When this has taken place, the tube is 
plunged into cold water. The paraffin solidifies, and the 
