80 THE COCKROACH : 



Popular books of natural history give striking and sometimes 

 exaggerated accounts of the prodigious strength put forth by 

 captive Insects in their efforts to escape. Thus we are told that 

 the flea can draw 70 or 80 times its own weight.* The 

 Cockchafer is said to be six times as strong as a horse, making 

 allowance for size. A caterpillar of the Goat Moth, imprisoned 

 beneath a bell-glass, weighing half a pound, which was loaded 

 with a book weighing four pounds, nevertheless raised the glass 

 and made its escape. 



This interesting subject has been investigated by Plateau, f 

 who devised the following experiment. The Insect to be 

 tested was confined within a narrow horizontal channel, which 

 was laid with cloth. A thread attached to its body was passed 

 over a light pulley, and fastened to a small pan, into which sand 

 was poured until the Insect could no longer raise it. Some of 

 the results are given in the following table : 



Table of Relative Muscular Force of Insects (Plateau). 



Weight of body Ratio of weight lifted 



in grammes. to weight of body. 



Carabus auratus 0*703 ... 17'4 



Nebria brevicollis 0'046 ... 25'3 



Melolontha vulgaris ... 0'940 ... 14'3 

 Anomala Frischii 0'153 ... 24'3 



Bombus terrestris 0'381 ... 14'9 



Apis mellifica 0-090 ... 23'5 



One obvious result is that within the class of Insects the 

 relative muscular force (as commonly understood) is approxi- 

 mately in the inverse proportion of the weight that is, the 

 strength of the Insect is (by this mode of calculation) most 

 conspicuous in the smaller species. 



In a later memoir^ Plateau gives examples from different 

 Vertebrate and Invertebrate animals, which lead to the same 

 general conclusion. 



* Haller. This and other examples are taken from Rennie's Insect Transformations, 

 t Bull. Acad. Roy. de Belgique, 2 e - Ser., Tom. xx. (1865), and Tom. xxii. (1866). 



Loc. cit. 3- Ser., Tom. vii. (1884). Authorities for the various estimates are 

 cited in the original memoir. 



