234 



BIOLOGY. 



[ROOK II. 



fifty to fifty-five in the green locust. Spite of the compara- 

 tive perfection of their respiratory apparatus and the activity 

 of their life, insects resist asphyxia a long time. Thus Lyonnet 

 saw caterpillars revive which had remained under water for 

 eighteen days. 



FIG. 28. 



A, posterior part of the larva of Ephemera vulgata :a, longitudinal trachean trunk ; b, in- 

 testinal canal ; c, trachean branchiae ; d, pluinous appendices of the tail. B. larva of 

 jEschna grandis (the dorsal part of the teguments is removed) : a, superior longitudinal 

 trachean trunks ; b, thin anterior extremity ; c, their superior part ramifying above the 

 rectum ; o, eyes. The figure C in the middle represents the intestine of the same larva, 

 seen sidewise : d, inferior lateral trachean trunk : e, communications with the superior 

 trunk ; a, b, c, as in figure J5. 



Must we, with Blainville, consider as aerian branchiae the 

 wings of insects, which are often the seat of an active circula- 

 tion 1 



The mollusfo, being for the most part aquatic, breathe through 



