50 C. M. JACKSON 



The average coefficient of variation for the viscera, taking all 

 ages together, is about 25. The average however is lowest at 

 birth and one week (22 or 23) and highest at three weeks (31), 

 resembling in this respect the variability in the weight of the 

 body as a whole. 



6. The coefficient of variation for the relative or percentage 

 weight is usually much lower than that for the absolute weight 

 of the various organs, as the growth of the organs is correlated 

 with that of the whole body more closely than with age. The 

 eyeballs, however, form a conspicuous exception to this rule. 



7. The highest degree of correlation with the body weight 

 (average coefficient 0.80 to 0.86) is found, not among the organs 

 of least variability (excepting the head), but among those of 

 moderate variability (kidneys, liver, lungs). Next come the 

 brain, heart and gonads (0.75 to 0.78). The remaining organs 

 are much less closely correlated with the body weight, the lowest 

 being the eyeballs and suprarenals (0.40 to 0.45). The average 

 coefficient of correlation, all ages together, is about 0.70. The 

 figures for coefficient of correlation are somewhat too high, being 

 augmented by a 'spurious correlation' due to the heterogeneity 

 of the weights when grouped at the age periods. Like the varia- 

 bility, the correlation appears lowest at birth and one week (0.63) 

 and highest at three weeks (0.85). Similarly the coefficient of 

 correlation appears usually higher in the male, as is also the 

 case with the coefficient of variation. 



BIBLIOGRAPHY 



Boas, F. 1897 The growth of Toronto school children, Report of U. S. Com- 

 missioner of Education, II. 



Boas, 0.0., and Wissler, O. O. 1904 Statistics of growth. Report U. S. 

 Commissioner of Education, I. 



Chisolm, R. a. 1911 On the size and growth of the blood in tame rats. Quar- 

 terly Jour. Exp. Physiol., vol. 4. 



CuRRiE, D. H. 1910 The rat and its relation to the public health (by various 

 authors). Public Health and Marine Hospital Service of the U. S. 



Davenport, C. B. 1904 Statistical methods with especial reference to biologi- 

 cal variation. 2nd ed.. New York. 



DissELHORST, R. 1898 tjber Asymetrien und Gewichtsunterschiede der Ge- 

 sahlechtsorgane, Archiv f. wiss. u. prakt. Thierheilk. Bd. 24. 



