TRANSFORMATION OF INSECTS 



cular organ for respiration, but their bodies are penetrate^ 

 in every direction by tubes, through which the air is trans 

 rnitted to every part. These tubes communicate externally 

 by openings called spiracles. To serve the purpose of a brain 

 and nervous system, they are furnished with two knottea 

 cords running the length of the-ir bodies. They possess the 

 senses of seeing, tasting, smelling, and feeling ; but organs 

 of hearing, if they exist, have not yet been discovered. They 

 are provided with a hard external covering which differs in 

 different species ; in some it forms a complete case of a 

 horny or shell-like substance ; and in others it consists merely 

 in a tough muscular coat, divided into rings which surround 

 the body. Their heads are furnished with anten'no) or feel- 

 erSj which are a kind of filaments composed of joints, de- 

 signed probably as the organs of the sense of touch, or of 

 sensations still more delicate and of a nature totally unknown 

 to us. 



The mouth oT insects varies much in construction, ac- 

 cording to the nature of their food. Some are armed with 

 a sort of lancet, and others with a trunk or probos'cis, which 

 in the butterflies is capable of being rolled up in a spiral 

 form. Their eyes may be considered among the most sur- 

 prising of nature's works. Tiiey differ much in form and 

 colour in the different insects ; but they are not, as might 

 be at first supposed, mere hemispherical bodies of plane sim- 

 ple surfaces, for examination proves them to be composed of 

 an immense assemblage of highly wrought hexagonal facets, 

 each furnished with its proper optic nerve, retina, and other 

 parts necessary for vision : the number of these facets dif- 

 fers in different species ; eight thousand have been counted 

 in the eye of the common fly, and twelve thousand in that 

 of the dragon fly. 



How sweet to muse upon His skill displayed ! 

 Infinite skill ! in all that he has made, 

 To trace in Nature's most minute design 

 The signature and stamp of Power Divine ; 

 Contrivance exquisite expressed v/ith ease, 

 Where unassisted sight no beauty sees ; 

 The shapely limb, and lubricated joint 

 Within the small dimensions of a point ; 

 Muscle and -n^rve miraculously spun, 



