INSECTS: THEIR BREATHING ORGANS 



123 



groves. It is remarkable that so complete is this repellent 

 power, that when the tail is at the surface, the animal may 

 make a very perceptible descent without breaking the con- 

 tinuity of the air, the surface presenting the curious phe- 

 nomenon of a deep funnel-shaped dimple leading down to 

 the tail of the animal. 



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

 so universally distributed as 

 that you may always calcu- 

 late upon being able to re- 

 peat these observations when 

 you will. I shall, therefore, 

 show you an analogous ex- 

 ample, much more easily ob- 

 tained. Both are inhabitants 

 of our fresh waters: the cha- 

 meleon-grub lives in ponds, 

 crawling among the stems of 

 aquatic plants, and occasion- 

 ally visiting the surface in 

 the manner you have seen; 

 but it is precarious in some 

 seasons not uncommon, in 

 others, scarcely to be met 

 with by the most persever- 

 ing 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 you. What, those 

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

 them, you will find them worth looking at. I dare say 



GRUB OF CHAMELEON-FLY. 



