JO FREDERICK S. HAMMETT. 



growth capacity of the body in weight, than does the growth 

 capacity of the bones in length differ from that of the body in 

 length. It falls in line with the interpretation that growth of 

 the bones in length is less systemically characteristic than growth 

 in weight; and that growth in bone length is more closely allied 

 to body growth in length, than bone growth in weight is allied to 

 body growth in weight. 



The table also shows that systemic association in both weight 

 and length is greater in the male than in the female. This 

 indicates that in the growing animal systemic association is more 

 dependent on general size factors in the female than in the male. 

 The relation is consistent with the fact show r n on the chart that 

 the degree of difference between the growth capacity of both 

 bones in weight and length, and that of the body, is greater in 

 the male than in the female. 



SUMMARY AND CONCLUSIONS. 



An evaluation of systemic and sex factors as determinants of 

 the type and rate of growth of the humerus and femur of the 

 albino rat has been made. 



The results of the analysis indicate that the influence of the 

 systemic factors is largely expressed as differences in degree, 

 while that of the sex factors is exhibited as differences in the 

 course as well as in the rate of growth. 



From the point of view of differential development, systemic 

 correlation is closer than sex correlation, both in rate and direction 

 of change, particularly during the period of active differentiation 

 (23 to 65 days of age). From this it is concluded that the sex 

 factors of influence, which apparently are gonadal in immediate 

 origin, are superimposed upon the systemic determinants and 

 direct the sex-specific course of development. 



REFERENCES. 



Donaldson, H. H., and Conrow, S. B. 

 '19 Quantitative Studies on the Growth of the Skeleton of the Albino Rat. 



Am. Journ. Anat.. Vol. 26, pp. 237-314. 

 Greenman, M. J., and Duhring, F. L. 



'23 ItrcvdinR and Care of the Albino Rat for Research Purposes. Wistar 

 Institute Press. 1'liila. 



