5ii() rills MK'UosroCK AND ITS ItKV KI.A'I'IONS. 



of Microscopic :;l.iidy, we in, TV most appropriate!! commence with 

 lidc-miicul Mini its appendages (scales, hairs, etc). The hody :i.nd 



their 

 mem- 

 bers are closely invested by :t hardened skin, \\lncli ;ic!s as I heir skeleton, 

 and all'ords points of a 1 1 achmenf to I he muscles hy which their sr\cral 

 parts are moved; being soft and llexible, however, at the joints. This 

 skin is usually more or less horny in its texture, and is consolidated hy 

 the animal substance termed ('Inline, as well as, in some cases, l>v a sma I 

 <|iianl ily of mineral matter. II, is in the ('<>/<<>/>/<'/<( that it- attains its 

 n-aicsl, development ; I he * dermo-skeleton ' of many licet les being so linn 

 as not only to confer upon them an c\l raordinary power of passive resist- 

 ance, 1ml, also to enahle them to put forth enormous force hy the action 

 of I he powerful muscles which arc attached to it. It ina\ he staled as ;i 

 ".encral ride, that. I he outer layer of I his dermo-skeleton is alwavs cellular, 

 hiking the place of an epidermis; and that, (lit 1 cells are straight-sided 

 and closely tilled togct her, so as to he polygonal (usually hexagonal) in 

 form. Of this' wo ha\e a- very good example in the s/t/icr/icitd layers 

 (Kig. 427, H) of the thin horny lamella' or hlades which constitute the 

 terminal portion of the antenna of the ('<>< &<//< r/cr (l<'ig. -lv<); this lavcr 

 being easily distinguished from Llie inlermediate portion (A) of the lamina 

 by careful focussing. In many Heel les, the hexagonal areolalion of the 

 surface is distinguishable when the light is relleefed from it at a particu- 

 lar jingle, even when not discernihle in transparent sect ions. The integu- 

 ment of I he common lint .\nl exhibits (lie hexagonal cellular arrangement 

 \ery distinctly throughout; and tho broad Hal. expansion of the lei;' of 

 I he ( 'ni/>ro (' sand-wasp ') all'ords anol her beau! ifnl example of a dist inct 1\- 

 cellular slrnclnre in the outer la\er of the integument. The inner layer, 

 however, which eonslilnles 1 he principal part of the thickness of 'the 

 horny easing of the IVcl le-t.rile, seldom exhihits any distinct organi/ji- 

 tion; though it may ht> usuallv separaleil into several lamella', which are 

 sometimes traversed by tubes that pass into them from the inner surface, 

 and extend towards I he outer wit bout reaching it. 



('I 1 .'. Tt-<innit<nf<tri/ .l/i/H'mtftycs. Tho surface of Insects is often 

 he <M, and is sometimes completely covered, with <t/>/><'>i(t(ti/t's, ha\ing 

 either the form of broad Hat Scales, or that, of Hairs more or less 

 approaching (he cylindrical shape, or some form intermediate belwiHMi 

 tho two. The fii-it/i/ investment is most complete nmonjj the l.c/nilofttrra 

 (Hntterily and Moth tribe); the distinguishing character of the insects 

 of this order being derived from the presence of a regular layer of 

 scales upon each side ot (heir l:irge membranous wings. ll is to the 

 peculiar coloration of the scales that the various hues and figures are 

 due, by which these wings are so commonlv distinguished; all the scales 

 of one patch (for example) being green, those of another red, and soon: 

 for the subjacent membrane remains perfectly transparent and colorless, 

 when (he scales have been brushed oil' from its surface. Kach scale 

 seems to he composed of two or more membranous lamella', often with 

 an intervening deposit of pigment, on which, especially in I.cpidoptera, 

 their color depends. Certain scales, however, especially in the Invlle- 

 tribe, have a metallic' lustre, and exhibit, brilliant colors that varv with 

 the mode in which the light- glances from them; and this ' iridescence,' 

 which is specially noteworthy in the scales of the Curruln) ini/writilift 

 ('diamond-beetle'), seems to be a purely optical clTeet, depending 

 either ^like the prismatic hues of a soap-bubble) on the extreme thinness 

 of the membranous lamella*, or (like those of 'mother-of-pearl.' ij f>tif>) 

 Oil a lineation of surface produced by their corrugation. Kach scale is 



