266 OUR HOUSEHOLD INSECTS 



constituted, would be as the weights of the animals them- 

 selves. The work done, therefore, being in the proportion 

 of the weights, and the energy available for doing it 

 bemg also in the same proportion, it follows that a leap 

 through equal distances would represent equal muscular 

 efficiency. And hence, on the above suppositions, a man's 

 leap of a single foot, instead of something like 500 feet, 

 would be more strictly comparable with a flea's leap of 

 one foot. The height of the leap, therefore, does not by 

 itself indicate any great superiority in relative muscular 

 strength 6n the part of the flea. 



But the question may be looked at in another light. 

 Plateau has recently carried out some investigations as 

 to the muscular strength of different insects by deter- 

 mining the maximum weight that they can lift; and 

 though the flea itself does not happen to have been 

 one of the insects experimented upon, yet the results 

 obtained will tend to throw great light upon our subject. 

 The modus op&randi was as follows : A narrow groove 

 was lined with cloth in order to give foothold, and the 

 insect to be tested was placed in the groove. One end 

 of a delicate thread was then attached to its body, and 

 the other passed over a small pulley at the end of the 

 groove. To the free end of the thread was attached a 

 small pan, and sand was put into this till the insect 

 could no longer raise it. The weight of the maximum 

 load having been determined, as well as that of the 

 insect itself, the ratio of the weight lifted to the weight 

 of the insect's body could at once be calculated. By 

 experimenting in this way with several well-known 

 insects, Plateau established some very curious results, 

 which at first sight seem rather paradoxical. He found 

 that the smaller the insect, the stronger relatively it 

 becomes, and that in every instance the strength is 



