462 PHYSIOLOGY. 



discovered in other animals, and is probably nowhere surpassed. I 

 think I discover the cause of this, for such small and insignificant 

 creatures, remarkable phenomenon in the preponderance of their 

 respiration ; for wherever we meet with the function of respiration, 

 and especially of the respiration of atmospheric air, preponderating, we 

 find in conjunction the faculty of powerful and continuous muscular 

 activity. Thus in this view also there is an affinity between insects 

 and birds, as both classes exhibit the high importance of respiration 

 to the entire organisation, and, as a consequence, the most powerful 

 muscular activity. 



The muscular power exhibits itself likewise in each of the four 

 several modes of motion. The rapidity with which certain insects 

 progress on foot is admirable, and presents itself in a very distinguished 

 degree in the last family of the beetles, namely, the Carabodea. Their 

 allies also, the Staphylini, display very rapid motions both in running 

 and in flight, but especially in the former. Even among the most 

 minute insects do we find rapid runners, for instance, among the flies, 

 in which the genus Tachydromia of the family Empidodea derive their 

 name from it. But it is not solely in the rapidity of their motions 

 that we recognise the muscular power of insects, but also in their 

 faculty of coursing about upon perpendicular walls and vibrating 

 surfaces. This faculty they especially owe to their sharp claws, and 

 to the clinging organs placed at the extremity of their foot. Many of 

 these, namely, the pulvilli of the bees, wasps, and flies, are true sucking 

 cups, which at first lay themselves flatly upon the object, and then by 

 their concavity and rarefaction of the air beneath them clutch closely 

 to it. But yet considerable muscular power is requisite for an animal 

 to continue hanging with its whole body suspended by its own limbs 

 by voluntary muscular force. 



Still more admirable is the rapidity with which many insects 

 that prepare for themselves cavities and subterranean dwellings are 

 able to execute them. This rapidity also presumes great muscular 

 power, and especially a great duration of the force. How rapidly, for 

 instance, does not the larva of the ant-lion dig its pit, which can 

 receive within its cavity at least a dozen insects of its own size ! How 

 speedily do not the fossorial wasps dig a hole for the reception of their 

 eggs after they have first placed in it a caterpillar as large as them- 

 selves, and frequently weighing at least half as much again ; and yet 

 the common Ammophila sabulosa carries off its prey with the greatest 



