178 



DISCOVERY 



Various screws and plungers serve tlie means of ad- 

 justing the shutter, focusing, and making the exposures. 

 At a depth of 15-20 feet the light is often good enough 

 to take a snapshot. The photograph of fish in motion 

 (Fig. 4) shows what sharpness of definition can be 

 obtained. But the excellence of the results tends to 

 obscure the great difficulty of manipulation and the 

 large series of failures through unavoidable accidents. 

 Clear though the water is, the almost impalpable 

 floating organisms and particles make it a much denser 

 medium than air and invest the colonies of corals, 

 branching like trees or massive like crags, witii an 

 air of unreality. For this reason the background of 

 the photograph rarely appears in focus. 



I can only call attention to one or two of the more 

 interesting observations on the habits of reef fishes. 

 They are not a homogeneous population, but can be 

 divided into sharply marked classes, according to their 

 habits, the parts of the reef they frequent and, particu- 

 larly, according to the periods of their activity. Some 

 are strictly diurnal like the well-known parrot fishes, 

 others confine themselves to the fissures of the reef 

 by day, like the "squirrel fishes," but the rays of a 

 torch cast on the water at night shows the surface 

 boiling with them. The enormous eyes and golden- 

 red colouring of these nocturnal kinds give them a 

 family likeness to deep-sea fish. Then there is a large 

 intermediate class, like the " pork fishes " (Antsotremus) 

 of the illustration, which feed actively at night, as 

 shown by an examination of their stomachs. During 

 the day, however, they do not retire within the crevices, 

 but lazily circle round some coral stack, without ever 

 taking food, and onlv show signs of returning activity 

 at twilight. 



How remarkable their colour patterns are, the pic- 

 ture of Anisotremits shows. This happens to be a 

 black and white fish, but the majority of the fishes 

 rejoice in gaudy colours — a habit to which the parrot 

 fishes owe their name. Many of them possess the faculty 

 of colour change to a remarkable degree. In Samoa, 

 for instance, Longley estimated that, out of 197 species 

 which he had under examination, there were 56 able 

 to change colour or pattern. This phenomenon may 

 be easily observed in the few aquaria (like New York, 

 Honolulu, or Madras) where tropical fish are housed, 

 but it requires very patient observation in natural 

 surroundings to estimate the value of these changes. 

 In some cases they are, possibly, as Townsend maintains 

 from his observations at the New York Aquarium, 

 the reflection of the varying emotions of the fish. 

 But for the most part, Longley concludes, the changes 

 are associated with the position of the fish against 

 different types of background, and afford the animal 

 protection by rendering it inconspicuous. Tempting 

 though it is to interpret the bold patterns and striking 



colours as warning signs, quite the contrary is the case, 

 for when seen in natural surroundings they blend with 

 the background. 



So much interest has been taken in the past in 

 geological and geographical problems of coral reefs 

 that their biological aspects are in some danger of 

 being neglected. This article is intended to show some- 

 thing of the results which are repaying the research 

 workers for their study in this comparatively new 

 field. 



BIBLIOGRAPHY 



The following is a short guide to the literature on the biology 

 of coral reefs. 



The Great Barrier Reef of A iislralia. W. SaviUe Kent. (Allen, 

 London. 1893.) 

 This is illustrated by the most splendid series of photographs 



of coral reefs ever taken and by indifferent coloured plates of 



fishes and other animals. 



The Fauna and Geography of the Maldive and Laccadive Archi- 

 pelagoes. J. Stanley Gardiner. (University Press, Cam- 

 bridge, 1903.) 

 A great deal of information of reef biology is contained in 



Professor Gardiner's general accounts in the first volume. 



Coral and Atolls. F. Wood Jones. (Lovell Reeve cS: Co., 

 London, 1912.) 



Corals and the Formation of Coral Reefs. Smithsonian Annual 

 Report of 1919. Thomas Wayland Vaughan. (Washing- 

 ton, 1919.) 

 An excellent resume of recent work. 



Marine Camo'ifleiirs and their Camouflage. The present and 

 prospective significance of facts regarding the coloration 

 of tropical fishes, Smithsonian Annual Report for 19 18. 

 W. H. Longley. (Washington, 1920.) 



Papers from the Department of Marine Biology of the Carnegie 

 Institute of Washington. By A. G. Mayor and Others. 

 1908 onwa.rds. 



The Flight from Reality 



By F. A. Hampton, M.C., M.B. 



It is probably as much to that faculty that we loosely 

 call imagination as to any other that man owes his 

 supremacy in the struggle for existence, for by it he 

 can make a picture of the future out of the experiences 

 of the past and so obtain a kind of fore-knowledge of 

 events which immensely increases his powers of 

 adaptation and the range of his achievements. 



But a certain price must be paid for this constructive 

 power of thought with the knowledge that it gives of 

 the possibilities of the future and the manifold and 

 remote consequences of an action, for man may well 

 find something a little daimting in the vision of reality 

 opened up by his far-reaching consciousness and by 

 the exquisite " awareness " with which it endows him. 

 And this v^ery business of adaptation to life is not 

 always an easy matter, more especially in a civilised 

 setting that has changed more rapidlv than the nature 



