78 THE entomologist's record. 



andata, L., AiitJircniis carius, F., Anthocoiiim fasciatus, L., Xeerobia 

 nijicollis, F., N. rufipes, F., Ptiiim fur, L., Nij^tus hululeiicus, Fald., 

 X. crenatii-s, F., Meziiuii ajfine, Boield., Anobium dumestlcum, Four., 



A. panicc'um, L,, Rhhopertha pmllla, F., JBlapn mui-ronata, Latr., 



B. Hunilis, Latr., Triholium fernujinewn, F., (Jnathocenis curnutiis, F., 

 Hijpopldoem depressUH, F., AlpJdtobius piceus, 01., Tenebrio ubaciirus, ¥., 

 T. molitur, L., Anthmis fioralis, L., Latheticiis ori/zae, 'W&t., Calandra 

 ;/ranaria, L., C. onjzae, L., PldoeophaijUH aeneupiceiis, Boh., Bruchiis 

 pisi, L., B. nijunanm, Boh., B. sp. (/), Chrysumela ;jraiiunis, L., 

 C fastuusa, L., Casaida viridis, L. 



On the wing=scales and their pigment in Lepidoptera. 



[Notes on Mr. Mayer's Paper.] 

 By T. A. CHAPMAN, M.D., F.E.S. 



I daresay attention will be called in the Record to a very able and 

 laborious paper by Mr. Alfred Goldsborough Mayer, on the " Develop- 

 ment of the wing scales and their pigment in butterflies and moths," 

 printed last June, for the Museum of Comparative Zoology, at 

 Harvard College, Cambridge, Mass., U.S.A., so that there will be no 

 necessity for me to point out the nature of the research, and the 

 general conclusions arrived at by Mr. Mayer. Having gone over a 

 great deal of the same ground several years ago, in investigating 

 the wing development during the pupal stage, with a view to satisfy 

 myself as to the real nature and meaning of " Poulton's line," I am 

 well able to appreciate the value of Mr. Mayer's work, and the general 

 accuracy of his determinations. I may say, in parenthesis, that the 

 questions I had raised for myself as to Poulton's line, were by no 

 means solved, and require further researches than I have yet been 

 able to make. 



There is only one point in Mr. Mayer's observations in which I 

 feel unable to agree with him, and therefore desire to call attention 

 to, in order that further observations may be made. It is very possible 

 that Mr. Mayer is correct, and that I am in error, but so many pupal 

 wings of the Vanessids, including several of P. atalanta, which gives most 

 facility for the observation in question, were examined by me at all 

 stages, that, were Mr, Mayer's conclusions correct, I can hardly 

 believe the matter would have appeared to me in such a different 

 aspect. 



Mr. Mayer says (p. 200) : " The protoplasm continues its retraction, 

 until finally it is entirely withdrawn from the scales, and they become 

 merely little flattened hollow chitinous sacs containing only air. The 

 scales are now completely formed, but they still lack the pigment, this 

 being introduced later. Owing to the fact that they are hollow, and con- 

 tain only air, they difiract the light, and therefore appear pure white, so 

 that the whole wing is now in the 'white stage.'" Again (p. 228): "Those 

 scales, which are destined to be white upon the mature wing, are 

 now completely formed, and undergo no further changes. Hence, 

 ontogenetically speaking, the white spots upon the wings are the 

 oldest of all. Those scales, which are destined to be pigmented, have, 

 however, a different fate ; for the " blood," or httmolymph of the 

 chrysalis, enters them, and they become completely tilled with the 

 fluid." 



