■u; 



PS re HE. 



[May— Juiu- i«i. 



the margin of a compartment diflerent 

 from the color of the midille of the com- 

 partment, as in the upper part of fig. 1 1, 

 b. The extreme margin of tiie scales 

 is always transparent and colorless, and 

 sometimes, as if by a flaw, a little 

 transparent spot extends into the colored 

 portion of the scale, as near the base of 

 fig. II, c. At all points along the mar- 

 gin where diflerent compartments meet 

 the marginal transparent ])ortion seems 

 to extend inward, and with higher mag- 

 nifying powers a very thin, transparent 

 partition can be seen extending between 

 the compartments. This jiartition is 

 clearly and perhaps too strongly repre- 

 sented on fig. II, rf and c. If a part 

 of a scale, especially near its base, is 

 broken, two edges can be readily seen, 

 showing the scale to be hollow, and the 

 color sometimes fails near the broken 

 edges. Everything indicates pigment 

 coloration, but experience with the 

 colored scales of Hoplia teaches the 

 application of reagents. Treatment 

 with the simplest of all reagents, water, 

 dispels all the illusion in regard to en- 

 closed pigments. Every scale that is 

 not absolutely perfect, becomes, in a 

 few moments, transparent and almost 

 colorless, a slight yellow remaining, the 

 water having entered the cracks and 

 broken places in the scales. Is the 

 pigment dissolved or changed cliemi- 

 cally bv the water.' This is negatived 

 by a few experiments similar to those 

 tried on the scales of lloplia. The 

 scales when rcdried from volatile liquids 

 regain their f)riginal coloration, the 

 same colors and shades in their respec- 

 tive compartincnts and locations. C'hlo- 



rin or sulphuric anhydrid (SO^) fails 

 to bleach the scales ; acids and alkalies 

 do not change their colors. Uninjured 

 scales are not penetrated by liquids and 

 remain colored in them. The coloration 

 is surely due, then, to physical causes, 

 that is to some form of interference of 

 light. 



The hairs are colored similarly to the 

 scales, although the finer hairs apjiear 

 to the naked eye, or to a simple lens, 

 as silvery white, even when seen on a 

 black surface. In the hairs the colors 

 often alternate in the same general man- 

 ner as tlicy do in tiie scales, but, as is 

 usual in the scales, vellow, or yellowish- 

 red, is generall)' nearest the basal portion 

 of the hair. The external transparent 

 sheath or wall of the hairs, correspond- 

 ing, as seen under the inicroscope, to 

 the transparent margin of the scales, 

 varies much in thickness; in some cases 

 the coloration fills nearly the whole 

 hair, in other cases the channel through 

 the hair is very small and consequently 

 the color line very narrow in the hair. 

 When treated with water or other liquids 

 broken hairs are rendered transparent 

 in the same manner as injured scales. 



Wiien filled with water the hairs and 

 scales still sliow, s')metimjs (juite dis- 

 tinctly, the partitions between their 

 diilercnt compartments. In rare cases 

 liciuiils tail to pass a p irlilit)n, leaving 

 one part of a scale or hair colored after 

 another part has been rendered trans- 

 puent. Thus it is evident that, how- 

 ever tliin the partitions may be, tlicy 

 are water-tight when uninjured : they 

 are, nevertheless, apparently usually 

 broken throucrli. the scales themselves 



