248 THE HISTORY OF CREATION. 
those of the left arm. Now, as the special use of the right 
arm has been adopted and transmitted by inheritance for 
thousands of years among Europeans, the stronger shape 
and size of the right arm have already become hereditary. 
P. Harting, an excellent Dutch naturalist, has shown by 
measuring and weighing newly-born children, that even in 
them the right arm is more developed than the left. 
According to the same law of divergent adaptation, both 
eyes also frequently develop differently. If, for example, a 
naturalist accustoms himself always to use one eye for the 
microscope (it is better to use the left), then that eye will 
acquire a power different from that of the other, and this 
division of labour is of great advantage. The one eye will 
become more short-sighted, and better suited for seeing 
things near at hand ; the other eye becomes, on the contrary, 
more long-sighted, more acute for looking at an object in the 
distance. If, on the other hand, the naturalist alternately uses 
both eyes for the microscope, he will not acquire the short- 
sightedness of the one eye and the compensatory degree of 
long-sight in the other, which is attained by a wise distribu- 
tion of these different functions of sight between the two 
eyes. Here then again the function, that is the activity, of 
originally equally-formed organs can become divergent by 
habit ; the function reacts again upon the form of the organ, 
and thus we find, after a long duration of such an influence, 
a change in the more delicate parts and the relative growth 
of the divergent organs, which in the end becomes apparent 
even in their coarser outlines. 
Divergent adaptation can very easily be perceived among 
plants, especially in creepers. Branches of one and the 
same creeping plant, which originally were formed alike, 
