December, 1905.] 



KNOWLEDGE & SCIENTIFIC NEWS. 



293 



At midnight of the 29th the glow was again seen, 

 and Dr. Xewcomb made the following note : — 



" 12 h. 5 m. to 12 h. 10 m. Local M.T. Tlx' 

 characteristic Zodiacal glow distinct and unmis- 

 takable — not so bright as ordinarily seen east or 

 west of the sun, yet several grades brighter than 

 the limit of doubt. It extends from a little east 

 of Capella to a region below the pointers. The 

 maximum of brightness is midway between Capella 

 and the north point, say between 10° and 150" 

 east azimuth and at 10° of altitude. The appear- 

 ance of maximum brightness below Capella was 

 evidently due to the Milky Way." 

 Dr. Newcomb (who also glimpsed the degenschein) 

 believes he has established the fact that in the direction 

 of the sun's axis the Zodiacal Light is brilliant enough 

 to be plainly seen to a distance of about 35° on either 

 side of the sun, and he suggests " that the Zodiacal 

 Light be hereafter described as a luminosity surround- 

 ing the sun on all sides, of which the boundary is 

 nowhere less than 35° from the sun, and which is 

 greatly elongated in the direction of the ecliptic." 



The Aurora, of November 151h. 



Bv W. Shackleton. 



A FIXE display of the Aurora Borealis was witnessed 

 in London on the evening of November 15. I first 

 noticed the phenomena at 9.10 p.m., when the sky 

 about 150 W. of N. appeared illuminated by a crimson 

 glow, with occasional crimson streamers, shooting up 

 towards the zenith. The crimson appearance, how- 

 ever, did not last very long, and by about 9.30 p.m. 

 had entirely disappeared. I was not able to com- 

 mence spectroscopic observations until the crimson had 

 disappeared, and then I could not trace any red line, 

 but over a considerable area in the sky the green 

 aurora line was very strong, together with two fainter 

 lines more refrangible and apparently a continuous 

 spectrum in the blue violet; the region of spectrum less 

 refrangible than the principal green line appeared a 

 perfect blank. Prof. Fowler informs me that he com- 

 menced observation shortly after 9.20 p.m., and was 

 able to trace the green line until 11 p.m.; he also state.s 

 that on the same morning he observed a brilliant 

 metallic prominence eruption on the W. limb of the 

 sun, and, in addition, there was considerable activity in 

 the large group of spots, in the western hemisphere, 

 as indicated by the reversals and displacements of the 

 bright lines, more especially C. (Ha.) 



R-oyal Geographical Society 

 Meetings. 



Secemter ;«.— Exploration in the Abai Basin, Abyssinia. By H. Weld Blundell. 

 December 2«.— Exploration in New Guinea (u-idi Cinematonraph niuatrntion^i. 

 By C. G. Seligman. 



other provisional arrangements are as follows : 

 Unexplored India. By Colonel Sir T. H. Holdich, K.C.M.G.. K.C.I. E., C.B. 

 The Economic Geography of Australia. By Prof. J. W. Gregory, F.R.S. 

 Survey and Exploration in Seistan. By Colonel A. H. McMahon. C.S.I. , CLE. 

 Exploration in Tierra del Fuego, By Captain Richard Crawshay. 

 Exploration in the East Tibet Borderlands. By Lieut. Filchner. 

 Explorations in Bolivia and Peru. By Baron Erland Nordenskjold. 

 The Philippine Islands. By Prof. AUeyne Ireland, 

 Northern Rhodesia. By L. A. Wallace. 



The Geographical Influences of Water Plants in Chile. By G. F. Scott Elliot. 

 Maps of London. By Laurence Gomme. 



TKe Coloration in. 

 MaLmmaLls ©Lnd Birds. 



By J. Lewis Bo.nhote, M.A., F.L.S., F.Z.S., 

 M.B.O.U., etc. 



.Xltmol'GH the literature on colour and coloration in 

 the animal kingdom has reached huge dimensions, and 

 the subject is one which has occupied zoologists from 

 the earliest days, yet we are still a long way from a 

 complete understanding of the causes and use of colour. 

 .\nd since any series of facts carefully collected, or a 

 suggestion, however slight, may prove a stepping-stone 

 towards a more complete knowledge of what are un- 

 doubtedly the most conspicuous features among 

 animals, I feel that no further excuse is necessary for a 

 paper of whose deficiencies no one is more conscious 

 than the writer. 



On the one hand chemists and physiologists have 

 restricted their investigations to the extraction and 

 analysis of pigments, and on the other hand the 

 majority of zoologists have studied coloration from the 

 standpoint of its utility to the organism in its environ- 

 ment. Few, however, have considered the fact that 

 colour has probably its primary cause and utility in 

 satislying some physiological need of the animal, while 

 natural selection has come in secondarily and eliminated 

 the unsuitable, or perfected those colours and markings 

 that were able to be adapted for purposes of protec- 

 tion, warning, itc. 



It is not my purpose here to enter into a long dis- 

 cussion, pointing out special cases where natural selec- 

 tion seems to have failed, or where its advocates seem 

 to have overstepped the limits of probability. This has 

 already been done by many writers, and although they 

 may have partially succeeded in showing that natural 

 selection is not sufficient to account for the cause of 

 coloration, yet their work has been, in the main, de- 

 structive rather than constructive, and it is probably 

 owing to this tendency that the physiological aspect of 

 colour is not more widely accepted to-day. 



I do not, therefore, propose in this paper to deal in 

 any way with natural selection, but, rather, to bring to 

 light further evidence in support of the contention that 

 colour is primarily due to the vigour of an animal, so 

 that where we find conditions suitable to a high state of 

 vigour we shall there find a corresponding increase in 

 the colour. 



Secondly, I shall try to show that many of the mark- 

 ings and longitudinal stripes on an animal will be 

 found to have their origin in certain spots, which I 

 propose to call '" poecilomeres," and I shall attempt to 

 bring forward considerable evidence to show that these 

 " poecilomeres " arise from physiological causes. 



Those who have kept and studied live animals know 

 that the state of the coat or plumage is an unfailing 

 criterion of health or sickness, and that without any 

 moult a bird, on recovering from an illness, becomes 

 much brighter and more glossy, and I know of a case 

 in which the black plumage of a bird became quite 

 brown during sickness, and re-gained, to a limited ex- 

 tent, its black and glossy appearance with the retuin of 

 health. 



We may, therefore, take it for granted that when an 

 animal's health becomes in any way affected, the change 



