2 ARON, 



The question of the influence of food on the process of growth is 

 by no means merely theoretical. It has an important bearing on prac- 

 tical j^roblems also^ for the study of nutrition in modern pediatrics is 

 gaining steadily in importance and much evidence has been accumulated 

 showing how closely food and development are related. Only a thorough 

 knowledge of the physiologic conditions of the process of growth and 

 of its relation to nutrition can furnish a scientific basis for the feeding 

 of infants as well as a clear insight into the problems involved. 



Eubner/ during the past two years, has published extensive studies 

 concerning the relationship of growth and nutrition. I have followed 

 his ideas as closely as possible in my introductory discussion and I 

 shall use his terminology, or the English equivalents, in preference to 

 that which I employed in a paper ^ on the same subject written before 

 his publication appeared. It is not my intention to discuss Eubner's 

 fundamental work; nor his demonstration that the problem of the 

 duration of life is involved in that of the number of calories metabolized 

 during life. His theory that man, in contrast to all other mammals, 

 occupies a particular position probably will not hold against the objections 

 made by other authors.^ However, Eubner's treatment of the funda- 

 mental questions concerning the application of the laws of energy to 

 the jjroblem of gTOwth furnishes the basis for all considerations and 

 investigations of this subject. 



The original cause of the process of growth is the "capability of 

 growing," as I have called it, or, better, the "tendency to grow," the term 

 used by Eubner. While we are fairly well informed concerning the 

 morphology of this process, its biology is dark. The "tendency to 

 grow" results from the tendency of the juvenile cells or the cells in 

 the juvenile organism to divide and to multiply. This tendency is 

 strongest in the very young animal; it gradually becomes less marked, 

 and finally is lost when the organism has grown enough; i. e., has 

 passed the period of youth and become an adult. An adult organism 

 under certain conditions may increase in certain parts of the body, but 

 these processes known as "hypertrophy" (called forth by an increased 

 demand of work on the muscles, heart, kidneys, etc.) or "pathologic 

 growth" (tumor) are markedly different from that which we term 

 "growth" in the sense of development. 



The "tendency to grow" has an upper limit. This means that more 

 than a certain quantity of new tissue can not be produced under any 

 circumstances. This upper limit is variable, not only for the same 

 Individual according to the stage of development or age, but also in 



^Arch. Hyg. (1908), 66, 1-208; Kraft und Stoff im Haushalte der Natur, Leip- 

 zig (1909), 116-17. 



"Biochem. Ztschr. (1908), 12, 28-77. 



^ Hans Friedenthal, Verhandl. d. physiol. GeselJschaft, Berlin (1909), 93, and 

 (1910), 22. 



