Correlation and Variation m the Toad 603 



seen that the external characters are about four times as variable 

 as the internal characters, a relation similar in general to that in 

 man where the internal characters are roughly four to five times 

 the more variable. Brain characters hold an intermediate posi- 

 tion being roughly only about twice as variable as external char- 

 acters. 



It is also significant that the variability of pure functions, as 

 far as they have been measured, is of the same general magnitude 

 as the variability of these internal organs. Table XXI summa- 

 rizes data collected by Pearson ('97) from various sources. 



TABLE XXI 



Coefficients of variability of junctional charactcistica in man 



C? 9 



Squeeze of hand (Porter) 29.30 1037.89 3^-41 fo 45.58 



Squeeze of hand (Galton) i3-4 21.4 



Squeeze of hand (Cambd. Anthrop. Com.) 13-64 (r) 18.42 (r) 



14-55(1) 18-78(1) 



Strength of pull (Cambd. Anthrop. Com.) 15-58 16.72 



Strength of pull (Galton) 15.0 19.3 



Strength of pull (Quetelet) 15-32' 22.62 



Keenness of eyesight (Galton) 28.68 S^-^i 



Keenness of eyesight (Cambd. Anthrop. Com.) 33-^5 3- -93 (0 



34-73 (0 



Dermal sensitivity (Galton) 35-7° 45-75 



Swiftness of blow (Galton) i9-4 I7- 1 



As an explanation of this difference in variability between inter- 

 nal and external characters Pearl ('05) has suggested tentatively 

 that the greater variability of the internal characters is due partly 

 to the fact that they depend to a very considerable degree for their 

 value upon the general metabolic condition of the organism as a 

 whole at the time of measurement, and partly to the fact that in 

 visceral characters the thing measured is not the thing with which 

 natural selection, as far as it has acted at all, has had to do. With 

 respect to the first suggestion it might be objected that while this 



tion "passively," /. e., whose value to the organism lies chiefly in position, or in a numerical or dimen- 

 sional relation. As internal we should include organs whgjse function is of a more "active" sort — mus- 

 cles, nerve-centers, glandular organs of all kinds, etc., structures whose value to the organism lies in a 

 metabolic rather than a mechanical relation. The distinction is not precise, certain organs may possess 

 values of both kinds, and yet the distinction is broad enough to be useful. 



