190 
of S. cerevistzae and with fresh beer-wort in the case of S 
anomalus were also prepared. 
For S. cerevisiae, 6, c, da, f, g, and 4 showed as good a spore 
yield as the control blocks, while a and ¢ gave a less abundant 
spore formation. Hence for this species comparatively great 
osmotic pressure variations had no effect on the spore formation, 
and it was only in the case of very large alterations that the 
yield was materially affected. 
For S. anomalus spores were only produced on the control 
blocks. This points to the fact that for this species the presence 
of food is a necessary condition, while variations of the osmotic 
pressure have little or no effect within moderate limits, since 
spores are formed when the blocks are kept moist with beer- 
wort of different strengths. 
Variations in the eration of the cells were then tried. 
Cultures were placed in (a) an atmosphere of pure 
CO ,, (6) air containing considerably more CO, than normal, (c) 
ordinary air, (@) air freed from CO, by potash.  S. cerevisiae 
and S. anomalus gave corresponding results. | No spores were 
produced in a or 6. Inc there was a good spore yield, and in 
ad an even better yield. The blocks used for the culture of 5. 
anomalus were moistened with fresh beer-wort instead of dis- 
tilled water. The eration, therefore, has a direct effect on the 
spore-production, the presence of CO, tending to inhibit it. 
The effect of moisture apparently varies according to the 
different conditions under which the experiment is conducted. 
Four cultures on gypsum blocks were placed as follows :— 
a. In air kept dry by calcium chloride. | No moisture 
added beyond that supplied by the few drops of beer- 
wort, which served as the source of the cells. 
= 
In ordinary air. Moisture added as in a. 
S 
In air. Blocks kept moist by addition of small quantity 
of distilled water. 
dad. In air. Blocks standing in distilled water. 
The results for S. cerevzszae showed that 4, c, and d gave very 
good yields of spores, but none were produced in a, the cells 
having dried up. ‘The results for c and @ hold good in those 
cases where the surface of the block is kept nicely moist without, 
however, becoming sloppy. Some gypsum blocks, on the addi 
tion of liquid, crumble somewhat and in cases the surface eX- 
posed to the air becomes pasty and the block is therefore 
rendered much less porous, and in extreme cases the beer-wort 
is never properly soaked up. Naturally, also, the eration of 
the cells on such blocks is very poor; and, as one would 
