514 Wager . — The Nucleus of the Yeast- Plant. 
embedded Yeast-cells may now be got at by breaking the 
tube carefully. The paraffin-block thus obtained is trimmed, 
fastened to the microtome, and cut in the ordinary way. The 
ribbon is fastened to the slide by cement, the paraffin melted ; 
the slide soaked in xylol, and finally mounted in balsam. In 
this way sections of the Yeast-cell are obtained in which the 
nuclear body can be very distinctly seen. Instead of carmine 
and nigrosin, haematoxylin may be used, according to Heiden- 
hain’s method. 
Other Methods of Mounting. 
Instead of being embedded in paraffin, the stained Yeast- 
cells may be mounted directly in balsam from the carbolized 
xylol. Care must be taken, however, to thoroughly break up 
the mass of cells with a brush on the slide in order to get an 
even regular layer. But perhaps the best method of doing 
this is to allow the cells, after carefully mixing them up with 
a brush on the slide, to dry up completely. By this means 
a single layer of cells only is obtained, if reasonable care be 
used. The slide can then be placed in xylol and mounted in 
balsam in the ordinary way. 
Another method which is very convenient is to allow the 
xylol to evaporate from the bottle, leaving the mass of Yeast- 
cells perfectly dry. Small quantities of this dried stained 
Yeast can be handed out to students, or sent by post in small 
packets without coming to any harm. It may be very easily 
examined. A small quantity is crushed up in water and 
either examined at once, or the water may be drained off 
by means of blotting-paper and dilute glycerin added. If 
a permanent preparation is desired, the cells which have been 
spread out in water on the cover or slip are allowed to dry up 
completely ; xylol is then added, and finally the preparation 
is mounted in balsam. This apparently rough treatment has 
very little, if any, effect upon the nuclear body ; but for the 
investigation of the more delicate structure of the Yeast-cell 
it is not to be recommended. 
