The Making of Species 
be correlated with organs or structures that are 
useful. 
Physiologists insist more and more upon the 
close interdependence of the various parts of the 
organism. All recent researches tend to show 
that each of the organs has, besides its primary 
function, a number of subordinate duties to per- 
form, and that the removal of one organ reacts 
on all the others. 
In face of these facts we should have expected 
those zoologists who have followed Darwin to 
have paid very close attention to the subject of 
correlation. Asa matter of fact, the phenomenon 
seems to have been almost completely neglected. 
This is an example of the manner in which the 
superficial theories which to-day command wide 
acceptance have tended to bar the way to 
research. 
There seems to be, in the case of some organ- 
isms, at any rate, a distinct correlation between 
their colouring and their constitution or mental 
characters. For example, the black forms of the 
cobra, the leopard, and the jaguar are notoriously 
bad-tempered. 
“There is,” writes Col. Cunningham, on p. 
344 of Some Indian Friends and Acquaintances, 
“much variation in the temper of different 
varieties of cobras, and, as is often so noticeable 
among other sorts of animals, there would seem 
to be a distinct correlation between darkness of 
358 
