Data for the Frohlem of F volution in 3fan. 



25 



for 1883, and is published in the 'B. A. Transactions' for that year, 

 p. 286. The measiu-ements were comparatively few in number (450 

 for each sex) and were made partly in London and partly in Edinburgh. 

 Accordingly I thought it better to obtain new material for calculating 

 correlation. Through the courtesy of Dr. J. D. Eawlings I was able to 

 obtain copies of the measurements made on between 2000 and 3000 

 new born infants at the Lambeth Lying-in Hospital. From these 

 1000 male and 1000 female babies born at the normal period were 

 taken, twins being excluded. The correlation tables and the calcula- 

 tian of the variation and correlation constants are due to Mr. L. 

 Bramley-Moore. The correlation tables seem of such importance for 

 medical and other purposes that they are given below (see Tables II 

 and III). The following table contains a summary of results. 



I. — Weight and Length of New-born Infants. 1000 of each Sex. 



Females . . . 



Mean. 



Standard devia- 

 tion. 



Coefficient of 

 variation. 



Coeffi- 

 cient of 

 correla- 

 tion. 



Weight. 



Length. 



Weight. 



Length. 



Weight. 



Length. 



Weight 



with 

 Length. 



lbs. 

 7 073 

 ±0-021 



ins. 

 20 -124 

 ± 0-025 



lbs. 

 1-006 

 ±0 -015 



ins. 

 1-177 

 ±0-018 



14 -228 



5-849 



0-622 

 ±0 013 





7-301 

 ±0-024 



20 -503 

 ± 0-028 



1-144 

 ±0-017 



1-332 

 ±0-020 



15 -664 



6-500 



0-644 

 ±0 -012 





Table I confirms the view already expressed by me, that the male 

 infant is at birth more variable than the female : that female infants 

 from six to ten years of age are more variable than male in both 

 weight and height, appears to be not a result of selection but of 

 growth."^ Both sexes lose not only variability but correlation as they 

 grow older, and this is a fundamental point to be borne in mind, when 

 attempts are made to trace the influence of natural selection in the 

 •change of variation or correlation in a group of growing animals. 

 Even the co-efficient of variation, which is far more stable than the 

 standard deviation (or absolute variability) is seen to alter considerably 

 with growth. So far as weight and height are concerned female and 

 male both lose variation as they grow older, but women less rapidly 

 than men. So far as correlation between weight and height is con- 



* See " Variation in Man and Woman," ' The Chances of Death,' vol. 1, 

 pp. 296, 307, aaid 308—309. 



