New YorK AGRICULTURAL EXPERIMENT. STATION. 169 
merely mechanical. Later, having acquired “vital energy” as 
a result of higher nutriment, the production of the wall-dis- 
solving enzym occurs and this aids in the subsequent spread of 
the fungus through the host tissues. 
TEMPERATURE. 
The optimum temperature for most rapid growth of B. caro- 
tovorus is in the neighborhood of 28° to 30° C., i. e., tubes will 
show clouding more quickly at this than at lower or higher 
temperatures. The presumption would seem to be that enzym 
production would be most active at this temperature, but our 
trials have shown otherwise. Where the enzymic activity of 
precipitates from broth cultures grown for eight days in the 
incubator at a constant temperature of 30° C. were tested in 
comparison with those grown at room temperature (18° to 
22°), the latter have shown distinctly more enzym than those 
grown in the incubator. We can offer no satisfactory explana- 
tion for this. Possibly comparisons at an earlier stage, say 
at three days’ growth, would have shown somewhat different 
results. It is also possible that the difference is due to less 
aeration in-the flasks held at the constant incubator tempera- 
ture than occurs in those at the frequently fluctuating room 
temperature. It is evident that this lack of aeration would 
have more inhibiting influence with the older growths than 
with the early clouding. The result convinced us that better 
enzym production could be had outside than inside the incu- 
bator, and since making these trials all our cultures have been 
carried at room temperatures. 
RELATION OF VARIOUS CONDITIONS TO THE 
ACTIVITY OF THE ENZYM. 
EFFECT OF LONG KEEPING. 
It is difficult to measure and record the rate of activity of 
such an enzym with a sufficient degree of accuracy to make 
exact comparisons. We have not succeeded in doing this to 
our entire satisfaction. So far as we can judge, however, 
