SAMUEL BRODY AND ARTHUR C. RAGSDALE 



633 



Table V shows the calculated and observed values during lactation. 

 The large deviation of the calculated values from the observed values 

 is in agreement with the established fact that lactation greatly retards 

 growth.^ 



TABLE V. 



SUMMARY. 



The growth period of the Jersey and Holstein cows is made up of 

 at least three cycles, two extrauterine cycles with maxima at about 

 5 and 20 months of age, and one intrauterine cycle, the maximum 

 of which has not yet been determined. The equation of an auto- 

 catalytic monomolecular reaction was found to give very good results 

 when applied to the cycle having its maximum at about 5 months 

 of age. The values obtained from this equation when applied to the 

 cycle having the maximum at about 20 months of age were higher 

 than the observed values probably due to the retarding effect of 

 pregnancy and lactation on growth. 



We are indebted to Dr. Walter R. Bloor and Dr. Carl L. A. Schmidt, 

 Department of Biochemistry, University of California, for valuable 

 suggestions. 



Psychol., 1905, xxv, 514. Eckles, C. H., Univ. Missouri Agric. Exp. Station, Bull. 

 135, 1915. Eckles, C. H., and Swett, W. W., Univ. Missouri, Agric. Exp. Station 

 Research Bull. 31, 1918. Regan, W. M., The efifect of lactation on growth. Thesis, 

 Columbia, 1914. Griswold, D. J., A study of the effects of the periods of ges- 

 tation and lactation upon growth and composition of swine. Thesis, Columbia, 

 1915. 



