CHAPTER XV. 



Peculiar Motions of Insects. 



NOTHING that has life seems capable of existing 

 long without motion. The oyster fixed upon the rock 

 must open and shut its shell, and the most gnarled oak 

 must wave its branches, otherwise their fluids will stag- 

 nate, and disease will ensue. In our own case, we 

 cannot, if we would, put a stop for any length of time 

 to all our motions. We have the power, indeed, of 

 interrupting the nictitation of the eyelids; but if we keep 

 our eyes fixed for a few minutes they become dry and 

 painful for want of the regular supply of moisture spread 

 over them by the process of winking. Breathing, again, 

 being a more important operation, cannot be long in- 

 terrupted, without serious consequences; and when the 

 motion of any of the limbs is prevented by the acci- 

 dental injury of its joint, it usually shrinks and dwin- 

 dles into less than half its natural magnitude, because 

 the proper quantity of the nutritive fluids is not impelled 

 thither in consequence of its deficiency of motion. 



We have already seen how indispensable the motions 

 of insects are to the due expanding of their wings upon 

 emerging from the pupa state; and several remarkable 

 circumstances show that, independent of change of 

 place in search of food or of other localities for their 

 progeny, motion is necessary to their well-being. At 

 least there does not seem any other plausible explication 

 of what we may term stationary motions. Kirby and 

 Spence's c motions of insects reposing,'* appears to be 

 a phrase which would not apply, for example, to an ox 

 chewing the cud, or a cat washing her face with her paw, 

 motions precisely similar to many of those of insects 



* Introd. vol. ii, p. 304. 



