412 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



neighborliood of the Montana camp, and a study of this group also 

 was begun. The continuation of this investigation is to be a major 

 feature of the investigations of the coming year. 



Cooperation with the Forest Service. — The value of grazing- 

 land areas in the national forests is not infrequently much impaired 

 by the presence of poisonoue plants. During the past year this office 

 has been able to point out the obnoxious features of the flora in cer- 

 tain forests and has endeavored to find means of diminishing losses. 

 I'he Forest Service has greatly aided the investigation and has ren- 

 dered substantial help in other ways. The cooperative work with the 

 Forest Service on grazing areas of the national forests will be con- 

 tinued, with special reference to certain of the forests in which the 

 sources of loss have not yet been determined. 



Laboratory studies. — Laboratory studies on the active principles 

 present in poisonous plants and their pharmacological action have 

 been continued by Dr. C. L. Alsberg and his assistants. Investiga- 

 tions of this nature are necessarily very technical and brief reference 

 only can be given them. 



One of the most important problems investigated was that of poi- 

 soning by prussic acid developed in sorghum and various wild grasses 

 and other plants. The investigation covered conditions leading to the 

 development of these poisonous properties. The laboratory studies 

 on the harmful principles present in poisonous plants, being of fun- 

 damental importance, are to be continued, with special reference to 

 the conditions giving rise to the prussic-acid problem. 



Miscellaneous poisonous-plant work. — The supposed harmful 

 action of rubber weed was studied in the spring in New Mexico, 

 where considerable losses of sheep were charged to this plant. 

 Losses due to Amianthium were again reported near Wilmington, 

 N. C, and material collected from the scene of loss yielded a highly 

 poisonous principle which is probably responsible for the harmful 

 result. The identification of suspected plant material is likely to be 

 a constant feature of the work. 



PHYSIOLOGICAL AND FERMENTATION INVESTIGATIONS. 



Many problems involving the behavior of crop plants and their 

 products arise which demand for their solution fundamental physi- 

 ological studies. As examples of such problems may be mentioned 

 the keeping qualities of fruits and vegetables as influenced by condi- 

 tions of production and storage, the growth and productiveness of 

 crop plants in relation to the methods and materials used in feeding 

 them, the effects of all classes of toxic compounds on the physi- 

 ological activities of the plant, and the nature and cause of disturb- 

 ances of function seen in physiological ailments such as the mosaic 

 disease. During the past year, work has been begun on several of 

 these problems. 



Fruit and vegetable storage. — Work carried on by Dr. Hein- 

 rich Hasselbring, in cooperation with Prof. L. C. Corbett, involves 

 technical studies of sweet potatoes before and during storage in 

 order to get an understanding of the fundamental causes affecting 

 their keeping qualities. The importance of this crop is much re- 



