EDITORIAL. 105 



constituents and their effeqt on plant growth, and summarized his 

 own recent investigations on the biochemistry of soils. Professor 

 Patten, of the Michigan Agricultural College, presented the chemical 

 status of soil phosphorus, and his associate, Mr. Robinson, discussed 

 the chemistry of humus. Dr. Headden, of the Colorado Agricultural 

 College, described the peculiar characteristics of Colorado soils and 

 gave the results of his investigations on the problems of alkali and 

 nitrates in those soils; Dr. E. J. Russell treated the production of 

 plant food in the soil, with special reference to the Rothamsted in- 

 vestigations on the effect of partial sterilization on the soil organisms. 

 Professor Jeffery, of the Michigan College, discussed various factors 

 affecting the functioning of soils, and his associate. Dr. Bouyoucos, 

 showed the radiating power of soils under various conditions. Dr. 

 Bizzell, of Cornell University, presented some of the results of 

 investigations by Dr. Lyon and himself on the problems of nitrifica- 

 tion and the colloidal matter in soils; Dr. Duggar, of the same insti- 

 tution, dealt with the roles of mineral nutrients in plant metabolism 

 and the fixation of nitrogen by soil organisms. Dr. Oscar Loew, 

 of the Hygienic Institute, Munich, Gennany, discussed the role of 

 mineral nutrients in animals and plants, especially in regard to lime 

 and magnesia. 



In the course in animal physiolog}^. Dr. Mendel discussed some 

 of the problems in the biochemistry of nutrition, and summarized 

 the newer researches on nutrition in growth and maintenance; Dr. 

 Sherman treated the functions of food and of the digestive fer- 

 ments and the utilization of specific food materials ; and Dr. Forbes, 

 of the Ohio Experiment Station, dealt with the mineral elements in 

 animal nutrition. Dr. C. E. Marshall, of the Michigan Agi-icultural 

 College, and his associates, Messrs. Brown, Giltner, Rahn, and Van 

 Suchtelen, discussed the biolog}' of the cell. Dr. Riddle's lecture 

 had to do with the phenomena of development, with special refer- 

 ence to color characters and the physiological basis of sex. The sig- 

 nificance and origin of sex differentiation and the inheritance of sex 

 Avere discussed b}^ Dr. Pearl, of the Maine Experim'ent Station. Mr. 

 Morse, of this Office, dwelt especially on the imj)ortance of the appli- 

 cation of physiological methods to live stock investigations and 

 instruction. 



In rural econmnics, Dr. Carver laid special stress on the econo- 

 mizing of human energy and of land in the rural industries, and the 

 general problems connected with the maintenance of the efficiency 

 of the rural population. Mr. Galpin, of Wisconsin University, em- 

 phasized the social factors of the rural conmiunity ; Dr. Hedrick, of 

 tlie Michigan College, spoke on human ecolog}^; Dr. "Warren, of 

 Cornell University, described the methods of making agricultural 



