THE DOMINANT INSECT 7 



its muscles be increased according to any uniform scale, 

 the sectional area of a given muscle will increase as the 

 square of any lineal dimension. But the weight increases 

 in a higher proportion, according to the increase in length, 

 breadth and depth jointly, or as the cube of any linear 

 dimension." This principle may be readily demonstrated 

 by a simple experiment in mechanics. We may first 

 take a cubical block of wood, and place it upon a square 

 column of the same material. If we now double all 

 the dimensions, which may be done by fitting together 

 eight cubes like the first, and four columns also the 

 same as before, but twice as long, we shall find that 

 each column has to bear double the original weight, 

 albeit the base of each, and consequently its strength, 

 remains unaltered. It is clear, therefore, that the 

 apparent strength of an insect is liable to misconception, 

 for the reason that its muscles have proportionately far 

 less work to do than those of larger animals, the con- 

 tractile, or pulling, force of each muscle increasing 

 rapidly as the size of the animal decreases. According to 

 Straus-Durckheim, a flea can leap a foot high — a feat 

 equal to raising 200 times its own weight ; yet this is 

 really less remarkable than a schoolboy's leap of two 

 feet, for it indicates exactly the same efficiency of 

 muscles and other leaping apparatus as would be implied 

 in a full-grown man's leap of the same height, viz. 

 one foot. 



When summing up the success-compelling attributes 

 of the insect, we must not ignore the changes of habit 

 which are accomplished during the progress of its life- 

 history. I shall deal more fully with this matter in the 

 next chapter. But I should like at once to remind the 

 reader that whereas a caterpillar eats leaves, a butterfly 

 sucks nectar from the flowers. This ability to feed in 



