396 INSECT TRANSFORMATIONS. 



former opinions on the flight of insects; yet it might 

 have been supposed, that in writing so voluminously 

 on the subject, he had left no point uninvestigated. 

 Nothing, however, can be more praiseworthy than 

 the candour (not very common in such cases) with 

 which Chabrier corrects his own mistake. 



In the two-winged flies {Diptcra) Chabrier de- 

 scribes two sets of muscular ribbons for putting the 

 wings in play — the dorsal, placed lengthwise, and 

 used to lower the wings, and the sterno-dorsal, placed 

 obliquely across these for raising the wings. In the 

 dragon-flies {LibelluUna), again, the disposition is 

 somewhat different, the stcrno- dorsal muscles being 

 placed intermediate, while another set of powerful 

 muscles, called pectoral, are placed lengthwise, and 

 are inserted immediately into the wings. In his first 

 work, our author thought these muscles acted sepa- 

 rately, but he now says they act in concert; and lie 

 is not now inclined to ascribe, as he at first did, 

 so much influence to the air in the interior of the 

 body, nor to the spring of the harder parts of the 

 back and breast. ' Certainly,' he adds, ' the elas- 

 ticity of these parts, and the re-action of the interior 

 air have their use : the fluid, particularly, contained 

 in their numerous vesicles, is, perhaps, very light, and 

 contributes to reduce the specific gravity of the 

 insect. Besides, by enveloping the interior organs, 

 it appears to me intended to protect these against 

 the violent motions of flight, and to contribute to 

 the expansion of the chest, dilating immediately 

 after being compressed by the contraction of the 

 muscles in the act of raising the wings. '^ 



It will appear, from this brief abstract, that the 

 subject is not a little interesting; yet it is not so easy 

 to throw it into a form hkely to be understood by a 

 general reader. Flying with wings, however, is a 



* M. Chabrier in Ann. des Soc. Nat., Avril 1829, p. 505. 



