EXPERIMENT STATION REPORTS. 211 



After a leave of absence of ten months at the Johns Hopkins Uni- 

 versity, I returned on July 1, 1922, to take up the work at M. A. C. 

 In the absence of Mr. H. C. Young, vi'ho spent the present year at Shaw 

 Botanic Gardens, St. Louis, Missouri, his problem on ''The Physiological 

 Effects on Life Processes of Certain Plants When Growing Under De- 

 ficient or Improper Nutritive Conditions" was discontinued. 



Mr. Paul Tilford, a senior student, assisted me as time allowed, in 

 both the experimental and the college work, and I Avish to draw atten- 

 tion to the fact that his work was excellent. 



The work in Plant Physiology has been divided between the College 

 and the Experiment Station. In the absence of Mr. Young and other 

 assistants, the college work has required more time. Further, the ap- 

 portionment of time this j^ear has been approximately two-thirds for the 

 College and one-third for the Experiment Station. 



Adamis Project: 



The Adams 2f project was continued, but work this year was carried 

 on entirely in the laboratory and the greenhouse. Field Avork, as con- 

 ducted in former years, was entirely out of the question in view of the 

 scarcity of funds. In the laboratory and greenhouse chief emphasis was 

 placed on a study of the influence of climatic conditions on the salt ratio 

 requirement of Marquis wheat. Two climatic conditions were studied, 

 and in this respect the natural conditions were called into use. The 

 first experiment was run in the early fall — SeptemlDer and Octo^ber, and 

 the second in late spring — May and June. 



My previous Avork had shoAvn that for different climatic conditions 

 a different salt ratio Avas required. This difference seemed to be ascrib- 

 able to the variations in light duration and intensity during different 

 experimental periods. The results of the experiments this year, hoAV- 

 ever, do not bear this out, for the same cultures that were best during 

 the September-October period remained the same high-yielding cultures 

 for the May-June period. The conclusion is inevitable; some other un- 

 known variable is acting'as a limiting factor. As in former years this 

 ])roblem continues to be interesting. As new vantage points are won, 

 others have to be attacked. Much progress has been made by different 

 investigators, and the work that I have done here and at Johns Hopkins 

 has brought out certain definite facts : 



1. No definite results that Avill stand statistical treatment can be 

 obtained Avith few plants in a culture. Ta'bles have been devised shoAV- 

 ing Avhat significance can be ascribed to cultures containing plants 

 numbering from 10-100. It has now been determined that from 40 to 

 50 plants should be used for each salt solution. 



2. With frequent changes (every other day) and with a lower total 

 condensation (1 atmosphere) the plants thrive better than ever before. 



3. Pure line seed, or seed of a single plant selection, give more uni- 

 form seedlings. 



4. Special methods for germination were devised. Through this 

 means more uniform seedlings were o'btained. 



It is interesting to find that after using the above methods, more con- 

 sistent results are obtained. For example, heretofore no definite com- 

 bination of salts seemed to be necessary for plant growth. The ratio 



