Ja-XUary 30, 19 1 3] 



NATURE 



593. 



that none of them had previously noticed tlie 

 phenomenon. 



The conditions were obviously special, although 

 frec|uently obtainable to one who deliberately set out 

 with the purpose of finding them. The sun was at a 

 low altitude on our left, and the wheat was soaking 

 wet with dew on our right. The dew speedily dries 

 up in the morning sun, and although I have kept on 

 the look-out for this phenomenon during the past 

 month I have never happened to pass a wheat-field 

 again with the conditions of time, situation, and wet- 

 ness repeated. 



I had, therefore, intended writing to Nature to 

 inquire whether the occurrence of these halos had 

 been previously recorded, and consequently was 

 greatly interested to read the note on p. 419 of your 

 journal (December 12, 1912) concerning Inada no 

 goko, or halo in the ricefield. I have not seen the 

 Japanese journal referred to, and consequently am 

 not aware if Profs. Fuchino .and Izu direct attention 

 to the fact noted above, that each observer sees the 

 halo round his own head only. This fact indicates 

 that the observer perceives those elements of a narrow 

 cylinder of the sun's ravs enclosing his head that 

 happen to be reflected back to his eyes by the dew- 

 drops and wheat blades ; the major portion of the 

 cylinder of light is reflected back along the cylinder, 

 and consequently a given observer is not in the line 

 of vision for the halo round another observer's head. 

 The explanation advanced by the Japanese observers 

 that the halo " is caused by the reflected light from 

 the sun-imatres formed on the green blades by the 

 passage of the sun's rays obliquely through ;)ie dew- 

 drops " is doubtless correct. I presume that their 

 investigations show that the farther a drop is from 

 the edge of the shadow of the head the smaller is the 

 proportion of the light reflected from the sun-images 

 that can reach the observer's eye : for the boundarv 

 of the halo is not sharp, the brightness diminishing 

 somewhat gradually with distance from the shadow. 

 Assigning to the head in the shadow the actual 

 diameter of the head, I estimated the noticeably bright 

 part of the halo as roughly 10 in. wide all round 

 the head, dying out on the shoulders. 



A close insnection of the green blades showed that 

 at or near the tip of each blade was one pearl of 

 dew, whilst the whole of the remainder of the blade 

 was coated with a film of minute dewdrops. It is 

 the minute drops that giv'e rise to the major portion 

 of the effect. 



Tho fact that each observer sees only his own halo 

 obviously precludes this phenomenon from having 

 been the origin of the halos recorded in sacred writ- 

 ings round the head of Christ and others. 



L. L. Fermor. 



Geological Survey of India, Camp, Korea State, 

 Central Provinces, January 4. 



Procryptic Coloration a Protection against Lions. 



There has been some interesting correspondence in 

 recent numbers of The Field on the question of the 

 procryptic coloration of big game, some writers taking 

 one side and some another in the controversy. Now 

 although there is a certain amount of evidence, scat- 

 tered throuirh sporting literature, showing that some 

 species of .\frican antelopps and zebras are hard for 

 human beings to detect in particular surroundings, 

 there is, so far as I am aware, scarcely any testi- 

 mony, based upon observation in the jungle, to prove 

 that the sisrht of predatory carnivora is baffled in the 

 samp way by colour assimilation. 



This question has such an important bearing on 

 the theory of the evolution, through natural selection, 

 NO. 2257, VOL. 90] 



of obliteralive coloration that I venture to repeat the 

 following story, told by Mr. F. C Selous {'I he Field, 

 January 18, p. 141), which I hold to be one of the 

 most valuable contributions to the subject ever pub- 

 lished, and worthy, as such, of being made known 

 to a much wider circle of zoologists than is comprised 

 by readers of The Field. Mr. Selous says : — ■ 



" I once wounded one [a lion] — a very savage lion, 

 I think — which at once came round to look for me. 

 I was sitting on the side of a large ant-heap, and no 

 doubt my bare sunburnt arms and legs, and the 

 dirty old shirt and towel in which I was dressed, 

 assimilated well with the colour of my surroundings, 

 for although the lion came and looked straight at me, 

 he could not make me out. I had not had time to 

 reload my single-barrelled rifle, but had a cartridge 

 in my right hand ready to slip into the open chamber 

 if the lion charged. But when he came towards me 

 and then stood looking at me, 1 did not make the 

 slightest movement, and he could not make me out. 

 and presently turned and looked the other way. . . . 

 I am perfectly certain that had I made the slightest 

 movement . . . this lion would have charged." 



Mr. Selous is a staunch opponent of the theory of 

 the survival value of oblilerative coloration in big 

 game, and his experience, above recounted, gains 

 force from the fact that it was described in an article 

 in which he was combating the double claim that the 

 equine and most of the ruminant mammals of Africa 

 are procryptically coloured and are benefited thereby. 

 But we shall probably have to wait many years before 

 we get a more cogent piece of evidence in favour of 

 the value to antelopes and other game of a combina- 

 tion of assimilative patterns with stillness. 



R. I. POCOCK. 



Zoological Society. 



Animal Coloration. 



.\n article by Dr. Francis Ward, illustrated by the 

 author's excellent photographs, appeared in the 

 December number of The Salmon and Trout Maga- 

 zine, which should not be missed by anyone who is 

 interested in the problem of animal coloration. With- 

 out attempting to discuss or give any rdsume of the 

 paper, there is one point to which 1 should like to 

 direct the attention of zoologists. 



Most visitors to the Natural History Museum at 

 South Kensington know of the ingenious device by 

 which Dr. Thayer demonstrated his theory of the 

 coloration of water birds. Two models representing 

 ducks are so arranged and painted that one of them 

 (.'\) is invisible until the observer comes close to the 

 case ; the other (B) is plainly to be seen from a con- 

 siderable distance. A has been coloured dark above 

 and light below, characteristic of most water birds, 

 B the reverse. Hence it is suggested that the colours 

 of aquatic birds are mainly protective against encniios 

 on the shore, and to a certain extent against raptorial 

 birds also. This theory has, I believe, met with much 

 favour from ornithologists, even if they have not 

 entirely accepted it. 



Dr. W'ard's results, however, seem to show that 

 the coloration of flesh-eating aquatic birds is rather 

 of an aggressive than of a protective nature, and that 

 the light colour on the underside of such birds renders 

 Ihem invisible to their prey beneath the water. Cer- 

 tainly his photographs are distinctly striking, especially 

 that of the heron and black-headed gull. It is much 

 to be honed that Dr. Ward will continue his observa- 

 tions " From the Fish's Point of ^■iew.'■ 



M. D. Hni. 



Eton College, January 21. 



