1916] EDITORIAL. 405 



normal growth in small and large animals — rats, swine, and cattle. 

 He emphasized especially the importance of exact Imowledge as to 

 the source, chemical composition, and relative proportions of the 

 nutrients used, and the essential need of the presence of food, though 

 in very small amounts, of at least two unlaiown substances. 



In the third week. Dr. B. M. Duggar, of the Missouri Botanical 

 Garden, gave five lectures on cellular entit}^ In these the present-day 

 knowledge and theories were clearly and impartially summarized, 

 including the morphology, structure, and chemical composition of 

 the individual cell, semipermeable membranes and related phe- 

 nomena, cell correlation in relation to growth, cell organization in 

 respect to reproduction, and the activities of the cell in regenera- 

 tion. At the seminars Dr. L. J. Henderson, of Harvard University, 

 took up the subject in its purely physico-chemical aspects and dwelt 

 particularly on the laws and hypotheses fundamental to our knowl- 

 edge of the cell, together with some of the more philosophical con- 

 siderations of the subject. 



Growth relations was the general topic of the lectures of Dr. H. C. 

 Cowles, of the University of Chicago, during the last week of the 

 course. Among the subjects treated were germination and growth, 

 vegetation activity in relation to light, vrater, etc., and reproductive 

 behavior as influenced by external factors. Plant interrelations were 

 also considered, such as antagonisms, illustrated by parasites and 

 epiphytes, the struggle for existence, including the ecology of weeds ; 

 beneficial relations, as illustrated by soil bacteria and fungi, and 

 reciprocal relations, as exhibited by legumes with bacteria, trees with 

 root fungi, etc. In connection with mass relations, soils and climates 

 as factors in associational development and change in composition 

 in relation to change in environment were discussed, and finally the 

 application of ecological factors to problems of crop production 

 was instructively presented. At the seminars Dr. Henderson dis- 

 cussed the physico-chemical properties of environmental factors, 

 with special reference to hydrogen, oxygen, and carbon, in their 

 more important combinations, and closed with some of the philo- 

 sophical aspects of environment. 



Parallel with the general course on growth an adjunct course 

 which embraced a systematic review of physico-chemical elements 

 involved in growth and their relation to biological processes was 

 given by Messrs. Anderson, Itano, Eobbins, Chapman, and Clark 

 of the Massachusetts College faculty. 



A week was devoted to discussions of the problems of education 

 with special reference to the training of students along agricultural 

 lines. Dr. W. C. Bagley, director of the school of education of the 

 University of Illinois, gave five lectures on the foundations of peda- 



