New Youk Auuicultuual ExrERiMENT Station. 19 



amoimt of moisture in air result in larger amounts of clieese to 

 sell and at the same time cheese of better quality. 



(2) A study of enzjfmcs 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. 



f^praijing experiments with crude petroleum. — ^Series I of these 

 tests included the experiments to determine the effect of crude 

 petroleum upon normal trees, and Series II tlie experiments to 

 determine the percentage of petroleum in an emulsion with 

 water required to kill the San Jos6 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 i^yc^'centages 

 caused serious injur}- 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 

 v/hile the 40 per ct. and higher percentages killed them in every 

 instance. 



