170 ANATOMY. 



with two curved air tubes between the pro- and mesc-thorax (PL III. 

 f. 7 and 8.) 



Among the Lepidoptera but one caterpillar, that of Botys stratio- 

 talis has been observed to possess branchiae *. In this they consist of 

 delicate small hairs which clothe the whole body, but particularly 

 laterally, in the vicinity of the future spiracles, they stand in fasciculi. 

 The tracheae are observed in them as glittering silver-white threads. 

 The caterpillar lives constantly in the water upon the leaves of Stra- 

 tiotes aloides. I have myself observed a very similar caterpillar of a 

 moth upon Ceratophyllum demersum, but I was not successful in 

 breeding it. Doubtlessly others also exist among the allied genera and 

 species, but which have hitherto escaped detection. It must strike as 

 remarkable, that among the Lepidoptera, which apparently, from the 

 great development of their organs of flight, are destined to dwell in the 

 air, larvae should be found which select a place of residence of such a 

 very opposite nature, whereas among the Hymenoptera, which appear 

 more adapted to dwell in a variety of media, no single instance 

 should occur of one having been observed, either in its larva or perfect 

 state, to live in water. It is indeed true that some of their larvae live 

 in moist places, such as the parasitic larvae of the Ichneumons, but 

 branchiae have never yet been detected in them. 



127- 



B. INTERNAL ORGANS OF RESPIRATION. 



The internal organs of respiration are the most simple and most 

 uniform parts found in the insect body ; for they universally present 

 themselves as ramose tubes originating from the spiracle, the exterior 

 air tube, or from the root of a branchia, and thence spread to all 

 the other organs. Malpighi, who by his dissection of the silk-worm 

 was the first to obtain a correct insight into the internal structure of 

 insects, was also the first discoverer of these internal organs ; pre- 

 viously it was thought that insects did not breathe, an opinion which 

 was originally propounded by Aristotle, and subsequently generally 

 received. 



As to the structure of these tubes serving for the function of respira- 

 tion, and which have been called AIR TUBES or TRACHEA, we shall find 



* DeGccr, vol. i. jart iii. PL XXXVII. f. .3 and 6. 



