34 a EXPERIMENT STATION. [Jan. 



occurred chiefly in houses where proper attention was not given 

 to ventilation. 



Further work with the powdery scab of potatoes indicates 

 that this in our climate will not become a serious disease. 



Dr. Chapman's investigations as to the mosaic disease of to- 

 bacco have been carried as far as at present seems desirable. 

 His conclusion is that the trouble is caused by disturbance in 

 the enzyme content of affected plants, and that serious losses 

 can be prevented by sterilization of the seed bed and the avoid- 

 ance of touching healthy plants immediately after touching or 

 handling those affected with the disease. 



The following articles by members of the department staff' 

 have been published during the year : — 



A. V. Osmun: Maple Anthracnose. Tree Talk, Vol. 4, No. 1, p. 21, 

 August, 1916. 



George H. Chapman: Effect of Colored Light on the Mosiac Disease of 

 Tobacco. Science, n. s., XLIII., pp. 537, 538, April 14, 1916. 



Orton L. Clark: A Method for Maintaining a Constant Volume of Nu- 

 trient Solutions. Science, n. s., XLIV., pp. 868, 869, Dec. 15, 1916. 



Department of Chemistry. 



The report for the department of chemistry covers the various 

 phases of its work, — research, control and miscellaneous. The 

 control work has already been sufficiently discussed (pages 18a- 

 21a). The miscellaneous work has been of the usual character 

 and volume, and does not require particular mention in this 

 place. 



xA.s usual, a large amount of attention has been devoted to a 

 study of the chemistry and determination of nutritive value of 

 different foodstuffs. Vegetable ivory meal, composed of shav- 

 ings from the corozo nut, received a large amount of attention, 

 and a paper reporting results has been published in the Journal 

 of Agricultural Research ("Chemical Composition, Digestibility 

 and Feeding Value of Vegetable Ivory Meal," Vol. VTL, No. 7, 

 pp. 301-320). The investigation made it apparent that this 

 material, notwithstanding its hard and refractory character, is 

 fairly digestible. It appears to be about equally digestible with 

 corn meal. 



