234 



BIOLOGY. 



[Book 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. 



3 



Fig. 28. 

 A, posterior part of tlie larva of Ephemera vulgata : — a, longitudinal trachean trunk j 6, in- 

 testinal canal ; c, trachcan branohise ; d, plainous appendices of the tail— S. larva of 

 ^schtM grandis (the dorsnl part of the teguments is removed) : — a, superior longitudinal 

 traeheau trunks ; J, thiu 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 B. 



Must we, with Blainville, consider as aerian branchise the 

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

 tion? 



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



