70 EXTERNAL ANATOMY OF INSECTS. 



fluids ; its mouth requires no hardness ; the bulk of its head 

 and body offers art. obstruction to its obtaining a sufficient 

 supply of its food, which is generally concealed in the nectary 

 of flowers ; the passage to the oesophagus is lengthened, and 

 the difficulty overcome. The caterpillar produces the butter- 

 fly ; one is haustellate, the other mandibulate : they cannot be 

 placed in separate classes. The mouth sometimes varies as 

 much and as abruptly in the same insect in its different stages, 

 as in any two different insects in their final stage. In others 

 it remains nearly the same, or gradually approaches its 

 perfection with every change of skin. In Orthoptera and 

 Hemiptera the latter is the case : in these classes, every 

 ecdysis is a metamorphosis ; the food and economy undergo 

 no change, the organs therefore require none. Nature never 

 provides uselessly. Fabricius beautifully observes, that it is 

 the part of the wise man to study these things ; to observe, 

 record, and add them to the stores of science ; to weigh well 

 the mysteries of Nature, and trace the hand of a Creator in 

 the wonders of his creatures. Lamarck says, that each 

 peculiar form has been acquired by degrees," and by striving to 

 attain a particular object." He appears to have forgotten, that 

 if honey had been denied to the bee until its little mouth had 

 lengthened out into a thread-like tube, starvation and extinc- 

 tion of its race must have been the consequence. Kirby, in 

 reference to this, exclaims, It is grievous that this eminent 

 zoologist, who in other respects stands at the head of his 



u La nature, clans toutes ses operations, ne pouvant proceder que graduelle- 

 ment, n'a pu produire tous les animaux a-Ia-fois : elle n'a d'abord forme que les 

 plus simples ; et passant de ceux-ci jusqu'au plus composes, elle a etabli suc- 

 cessivement en eux differens systemes d'organes particuliers, les a multiplies, en 

 a augment^ de plus en plus Pimergie, et, les cumulant dans les plus parfaits, elle 

 a fait exister tous les animaux connus avec l'organisation et les facult^s que nous 

 leur observons. — Lamarck. An. sans Vert. 



1 Premierement, quantite de faits connus prouvent que l'emploi soutenu d'un 

 organe concourt a son developpement, le fortifie, et l'agrandit meme ; tandis 

 qu'un defaut d'emploi, devenu habituel a l'egard d'un organe, nuit a ses develop- 

 pemens, le deteriore, le reduit graduellement, et finit par le faire disparoitre, si 

 ce defaut d'emploi subsiste, pendant une longue duree, dans tous les individus 

 qui se succedent par la generation. On concoit de la qu'un changement de 

 circonstances forcant les individus d'une race d'animauxa changer leur habitudes, 

 les organes moins employes d£perissent pen a peu, tandis que ceux qui le sont 

 davautage, se developpent mieux et acquierent une vigueur et des dimensions 

 proportioHnelles a l'emploi que ces individus en font habituellement. — Lamarck. 

 Phil. Zool. 



