52 THE MICROSCOPE AND ITS LESSONS. 



passage right down to the end of the tongue of the per- 

 fect insect, keeping the long air-tubes from collapsing, 

 and providing a safe passage for the life-giving air, 

 which would appear to be sifted from all impure sub- 

 stance before entering the body by the sieve-like spiracle, 



Trachea; of a beetle. 



and then, when thus purified, supplying this humble 

 creature with the first element of life. 



Now behold the pupa, which, observe, has just escaped 

 from the very admirably contrived pupa-case. It is no 

 stretch of the imagination to call this empty cell a coffin, 

 and the " transition " a veritable resurrection. There are 

 the shrivelled remains of life number one attached to the 



