THE RATE OF GROWTH OF THE DOMESTIC FOWT.. 



By SAMUEL BRODY. 



{From the University of Missouri Agricultural Experiment Station, Columbia.) 



(Received for publication, February 24, 1921.) 



If the weight of a mammal, for example the mouse, is plotted against 

 its age, the resulting curve will be seen to show three fairly distinct 

 waves, oscillations, or growth cycles. These waves or cycles are 

 still more strikingly shown by plotting the velocity of growth against 

 age as is seen in Fig. 1. 



Robertson^'^ found that the growth of each of these cycles can be 

 represented by the equation of an autocatalytic monomolecular 

 reaction. This fact, and the theories developed from the fundamen- 

 tal studies on cell growth by Sachs, Morgan, Driesch, Boveri, and 

 Loeb,^ which were reviewed in a previous paper^ on the growth of 

 the dairy cow, led Robertson^'2 and Ostwald'^ to assume that the lim- 

 iting factor of growth of each cycle is an autocatalytic monomole- 

 cular reaction. Assuming this tricycHc and autocatalytic theory 

 of growth to be true for mammals, it becomes of interest to find out 

 whether the same does not also hold for birds. The object of this 

 paper is to examine data on the growth of the domestic fowl in the 

 light of this theory. 



Fig. 2, deduced from Table I, shows the rate of growth of the Rhode 

 Island Red breed of fowP from the time of hatching up to the age of 



1 Robertson, T. B., /. Biol. Chem., 1916, xxiv, 363. 



^Robertson, T. B., Arch- Entwcklngsmechn. Organ. 1907-08, xxv, 581; Am. 

 J. Physiol., 1915, xxxvii, 1, 74; Principles of biochemistry, for students of medi- 

 cine, agriculture and related sciences, Philadelphia, 1920. 



^ Loeb, J., The dynamics of living matter, New York, 1906, 58-66; Biochem. 

 Z., 1907, ii, 34; Biol. Centr., 1910, xxx, 347. 



^Brody, S., and Ragsdale, A. C, /. Gen. Physiol., 1920-21, iii, 623. 



^ Ostwald, W., Vortrage and Aufsatze iiber Entwicklungsmechanik der Organ- 

 ismen, Leipsic, 1908, v. 



^ Card, L. E., and Kirkpatrick, W. F., Starrs Agric. Exp. Station, Bull. 96, 1918. 



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