704 EXPERIMENT STATION RECORD, 



pot and plat work, might be carried on in such wa}^ that the student 

 could determine for himself the important facts in the mineral nutri- 

 tion of plants. This is one of the plant activities that can be rather 

 definitely controlled, and the fimdamental principles underlying the 

 application of fertilizer elements should be thoroughly mastered. 



Photosynthesis, which is very little subject to control or regula- 

 tion, is generally studied where laboratory work is done, while other 

 functions that may be definitely directed to the advantage of the 

 crop and the profit of the grower are neglected. Respiration, the 

 response to stimulus, and the physiology of reproduction, are usually 

 passed over with slight attention, although all of these fimctions have 

 a direct bearing on the welfare of the plant. 



In the field of investigation, one aspect of plant physiology is 

 almost wholly overlooked, that is, the relation it bears to plant dis- 

 eases. So long as the normal functions of the plant are not fully 

 understood it will be impossible to know very much of the abnormal 

 or pathological conditions. Studies are generall}' made of the or- 

 ganisms which cause disease, and experiments are conducted that 

 look to controlling their spread, but very few investigations are 

 undertaken to determine the nature of the effect of the parasite on 

 its host, or as to how the injury is brought about. The study of 

 plant diseases due to fungi and other organisms receives much atten- 

 tion, but the large and important class of plant injuries due to what 

 are usually designated physiological disturbances receives rather 

 scant study. True, little is known of how these disturbed conditions 

 are brought about, but this lack of knowledge should stimulate in- 

 vestigation along this line. In the treatment of plant diseases the 

 outward manifestations are usually given more consideration than 

 the constitutional changes produced. As long as this is true, preven- 

 tion rather than cure will be the result. But even in the prevention 

 of plant diseases very little is known as to the principles underlying 

 immunity or resistance to the attack of certain organisms. 



Some of the above statements are not intended to apply to the 

 teacher alone. Investigators are needed to clear up many little 

 known facts concerning the activities of plants. But if more em- 

 phasis were given to the importance of a study of plant physiology 

 in its agricultural relations, more investigators would be trained who 

 might address themselves to the problems in that field. 



The extent to which the physiological aspects of plant growth are 

 studied or taken account of in connection with field experiments 

 seems quite inadequate. These experiments are extensive in number 

 and constitute a large feature of experiment station work. But 

 much as we discuss their importance and their limitations, and at- 

 tempt to provide greater accuracy, features of great significance are 



