New York AGRICULTURAL EXPERIMENT STATION. 19 
amount of moisture in air result in larger amounts of cheese to 
sell and at the same time cheese of better quality. 
(2) A study of enzymes in cheese—Methods of making and curing 
cheese improve slowly, because we do not yet know with cer- 
tainty what agent or agents are the causes of cheese ripening. 
During the past three years the chemical and bacteriological 
departments have been making a careful study of the factors 
that are commonly regarded as the active ones in producing 
ripening of cheese. The results, as far as published, appear to 
indicate that neither the enzymes secreted in cows’ milk nor 
those produced by bacteria in the milk previous to its being 
made into cheese are to be regarded as the most prominent 
factors in normal cheese ripening. 
DEPARTMENT OF ENTOMOLOGY. 
Spraying experiments with crude petroleum.—sSeries I of these 
tests included the experiments to determine the effect of crude 
petroleum upon normal trees, and Series II the experiments to 
determine the percentage of petroleum in an emulsion with 
water required to kill the San José scale. Three hundred and 
twenty-one fruit trees were included in these experiments, con- 
sisting of apples, cherries, pears, peaches and plums. The 
results were fairly uniform. In the experiments of Series I no 
injury was caused by the 25 per ct. emulsion except to peach 
trees, but in every-case 40 per ct. and higher pcrcentages 
caused serious injury to European plum trees, and to apple trees 
when the emulsion was applied during the fall or winter. Early 
spring applications of the 40 per ct. emulsion did not injure 
apple trees. Pear and cherry trees were not harmed by the 
emulsion or undiluted petroleum even when applied during the 
fall or winter. 
The experiments to ascertain the percentage of petroleum 
required to kill the hibernating scales also gave uniform results. 
The 25 per ct. emulsion failed to affect the scales materially 
while the 40 per ct. and higher percentages killed them in every 
instance. 
