insects: their breathing organs. 103 



series of not very close-set branchlets, set like the plumes 

 of a feather, or the pinnae of a fern-leaf, which give it 

 the elegant plumose appearance which the unassisted eye 

 recognises. The bristles have a granulose surface near 

 the extremity, and terminate in fine points. 



The curious faculty of repelling water, which the in- 

 terior surface of this plumy coronet possesses, is of the 

 highest value in the economy of the insect ; for, on the 

 one hand, it permits the breathing orifice to be brought 

 into contact with the air, even when nearly a quarter of 

 an inch below the surface ; and, on the other hand, it 

 allows the volume of air inclosed within the funnel to 

 be perfectly isolated, and carried securely away, as a 

 reservoir for the wants of the animal, when engaged in 

 its avocations of necessity or pleasure, in the recesses of 

 its sub-aquatic groves. It is remarkable that so com- 

 plete is this repellent power, that when the tail is at the 

 surface the animal may make a very perceptible descent 

 without breaking the continuity of the air, the surface 

 presenting the curious phenomenon of a deep funnel- 

 shaped dimple leading down to the tail. 



The chameleon-fly is not, however, so abundant and so 

 universally distributed as that you may always calculate 

 upon being able to repeat these observations when you 

 will. I shall, therefore, show you an analogous example, 

 much more easily obtained. Both are inhabitants of our 

 fresh waters : the chameleon-grub lives in ponds, crawling 

 among the stems of aquatic plants, and occasionally visit- 

 ing the surface in the manner you have seen ; but it is 

 uncertain^; in some seasons not uncommon, in others, 

 scarcely to be met with by the most persevering search. 

 For my next specimen, I have but to go with a basin to the 

 water-butt in the yard, and take a dip of the surface-water 

 at random : I shall be pretty sure of a score at least. 



Here they are swarming, as I told yon. What, those 

 tilings'? why, they are gnat-grubs. Well, don't despise 



