Dr. N. L. Britton, Director-in-Chief. 



Sir: I have the honor to submit the following report for 

 the year 1910. 



The laboratory equipment has been extended by the 

 addition of several pieces of apparatus to be used in student 

 investigation; and the chemicals, reagents, and general 

 supplies which have been used during the course of such 

 investigations have been replaced. 



During the autumn, Dr. W. J. Gies, Consulting Chemist 

 of the Garden, assisted by Dr. E. D. Clark, made use of 

 the chemical laboratory on Wednesday of each week. 

 The work offered at this time consists of a laboratory 

 course in plant chemistry for the benefit of graduate stu- 

 dents in Columbia University. The object of this course 

 is to stimulate investigation of original problems in plant 

 chemistry. Some of the chemical problems under investi- 

 gation are: the chemistry of poisonous mushrooms, the 

 chemistry of soil sterilization and its relation to the growth 

 of plants, and a study of the action of the oxidizing enzymes 



Insect Pests and Plant Diseases 



The spraying of the coniferous trees with whale-oil 

 soap solution has been continued as usual. The elm trees 

 in the Garden were sprayed with arsenate of lead, once 

 soon after the leaves unfolded in the spring and again 

 in the early part of June, and the smaller trees were sprayed 

 a third time. During mid-summer, the trees in the Garden 

 which had been sprayed showed much less injury from the 

 attacks of the beetle than those outside of the grounds 

 which had not been treated. Being absent from the city 

 after the middle of August, I was unable to observe con- 

 ditions, but the spraying was doubtless attended with 

 very satisfactory results. 



