THE EATE OF GROWTH FOLLOWING AN INITIAL 

 PEEIOD OF SUPPRESSION^ 



DR. HOWARD 



The present ])i\\)rr ;itteiii])t.s to discuss quantitative 

 aspects of the growtli of animals which, though eventually 

 reaching the same approximate size, reached that size 

 at widely different ages. The data upon which the dis- 

 cussion rests have been drawTi from the published articles 

 of several workers in the field of animal physiology and 

 deal with the growth, under varying conditions, of the 

 albino rat. 



When the grow^th of an animal is suppressed for a long 

 time the capacity to grow persists, even beyond the 

 period at which growth ordinarily ceases in that species. 

 The studies of Osborne and Mendel have amply demon- 

 strai(Ml Iho existence of lliis cnpacltv \o -row and to 

 ivnch the uvi-ht rlianirt.rjstic o\' matuiv individuals of 



in the organism. The environment, while modifying the 

 amount of growth, has less influence upon the specific 

 character of the growth of organisms than has the es- 

 sential constitution of the living substance. A quantita- 

 tive study of the growth rate of organisms ought, there- 

 fore, to lead to considerations of a fundamental nature. 



The nature of the growth rate in general is revealed by 

 the use of a few simple equations of the first order. They 

 show that growth proceeds at a rate similar to that of a 

 monomolecular reaction. Robertson^ and others have dis- 

 cussed growth in its relation to autocatalysis. In a recent 

 ])aper I have eom])arod the equations of slowly and rap- 



