322 THE WORLD OF LIFE 



neither head nor legs, while the third have both head and legs, 

 and are also variously coloured, and often possess spines, horns, 

 hair-tufts, or other appendages. 



Every one knows that a caterpillar is almost as different 

 from a butterfly or moth in all its external and most of its 

 internal characters, as it is possible for any two animals of 

 the same class to be. The former has six short feet with 

 claws and ten fleshy claspers; the latter, six legs, five- jointed, 

 and with subdivided tarsi; the foi-mer has simple eyes, biting 

 jaws, and no sign of wings; the latter, large compound eyes, 

 a spiral suctorial mouth, and usually four large and beauti- 

 fully coloured wrings. Internally the whole muscular system 

 is quite different in the two forms, as well as the digestive 

 organs, while the reproductive parts are fully developed in 

 the latter only. The transformation of the larva into the per- 

 fect insect through an intervening quiescent pupa or chrysalis 

 stage, lasting from a few days to several months or even years, 

 is substantially the same process in all the orders of the higher 

 insects, and it is certainly one of the most marvellous in the 

 whole organic world. The untiring researches of modern ob- 

 servers, aided by the most perfect microscopes and elaborate 

 methods of preparation and observation, have revealed to us 

 the successive stages of the entire metamorphosis, which has 

 thus become more intelligible as to the method or succession 

 of stages by which the transformation has been effected, though 

 leaving the fundamental causes of the entire process as mys- 

 terious as before. Years of continuous research have been 

 devoted to the subject, and volumes have- been Avritten upon it. 

 One of the most recent English writers is Mr. B. Thompson 

 Lowne, F.E.C.S., who has devoted about a quarter of a cen- 

 tury to the study of one insect — the common blow-fly — on 

 the anatomy, physiology, and development of w^hich he has 

 published an elaborate work in two volumes dealing with every 

 part of the subject. He considers the two-winged flies to be 

 the highest development of the insect-type ; and though they 

 have not been so popular among entomologists as the Coleoptera 



