298 THE WORLD OF LIFE 



completely unlike their perfect condition. They comprise 

 the great orders Lepidoptera (butterflies and moths), 

 Coleoptera (beetles), Hymenoptera (bees, ants, etc.), and 

 Diptera (two-winged flies), the first and last being those 

 which are perhaps the most important as bird-food. In all 

 these orders the eggs produce a minute grub, maggot, or 

 caterpillar, as they are variously called, the first having a 

 distinct head but no legs, the second 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 former has simple 

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

 compound eyes, a spiral suctorial mouth, and usually four 

 large and beautifully coloured wings. 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 perfect 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 observers, 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 mysterious 

 as before. Years of continuous research have been devoted 

 to the subject, and volumes have been written upon it. One 

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

 Lowne, F.R.C.S., who has devoted about a quarter of aj 

 century to the study of one insect — the common blow-fly — 



