August 24, 1882] 



NATURE 



389 



sketches under water in his diving-bell, give a striking 

 representation of the coral insect " in his habit as he 

 lives." For my own part, it is nine years since, m the 

 spring of 1873 I visited the coral banks of Tur at the foot 

 of Sinai, and there first became acquainted with the 

 wonderful manifestations of life in this submarine fairy 

 land. My interest was roused to the highest pitch, and I 

 endeavoured, in my popular treatise on "Arabian Corals" 

 (Berlin, 1876), briefly to describe the organisation of these 

 curious animals and their mode of life in common with 

 that of various other creatures. The corals of Ceylon as 

 I studied them at Galle, and afterwards in more detail at 

 Belligemma, recalled pleasant memories and enriched 

 my mind with a store of fresh observations." 



" The marine fauna of Ceylon is indeed closely related to 

 that of the Arabian shore of the Red Sea, the two having 

 many genera and species in common. But in number 

 and variety of forms of life, the extensive bay of the 

 Indian Ocean with its varied coast formation is far richer 

 than the confined Arabian Gulf where the conditions of 

 life are simpler and more uniform, and I found consider- 

 able variations underlying the apparently similar physiog- 

 nomy of the coral banks in the two districts. Those of 

 Tur were chiefly characterised by warm tones, such as 

 yellow, orange, or red, while the coral groves of Ceylon 

 displayed little but green in every variety of shade. 

 Yellow green Alcyonaria alternated with sea-green 

 Heteropora, malachite green Anthophylla with olive- 

 green Millepora, emerald green Madrapora and Astraea 

 with brown-green Montipora and Maeandrina. Ran- 

 sonnet has justly remarked on the predominance of green 

 throughout the island of Ceylon. Not only is this 'ever- 

 green isle' decked the whole year through with verdure 

 that never fades, but even the animals that inhabit it are 

 for the most part green in colour. The most frequently 

 occurring birds and lizards, butterflies and beetles, are of 

 a brilliant green hue : so also are many of the fishes and 

 crabs, Amphinomao and Actinia; even animals which 

 elsewhere are seldom or never green, here don the prevail- 

 ing livery ; such are star-fish {Ophiurida), sea-urchins, sea- 

 cucumbers, giant-mussels ( Tridacnd), and many others. 

 The explanation of this remarkable phenomenon must he 

 sought for in the Darwinian theory of development, 

 especially in the law of adaptation as applied to the 

 ' sympathetic selection of colour,' which I have demon- 

 strated in my 'Natural History of Creation' (seventh 

 edition, p. 235). The less the colour of an animal differs 

 from that of its surroundings, the less likely it is to attract 

 the attention of its enemies ; it is better able also to 

 approach its prey unobserved, and its chances in the 

 struggle for existence are thereby indefinitely increased." 



"Natural selection will strengthen the resemblance in 

 colour between animals and their surroundings, as being 

 of advantage to the former. The coral banks of Ceylon, 

 with their inhabitants, afford as good an illustration of 

 this theory as the animals dwelling in the woods and 

 thickets of the island, and in purity and brilliancy of 

 colour the former have a distinct advantage. It would 

 be a great mistake to imagine that an effect of monotony 

 resulted from this tendency to uniformity of colour. On 

 the contrary, the eye is never tired of admiring the mani- 

 fold combinations and modifications which occur, and 

 which are heightened by the not infrequent juxtaposition 

 of other colours. Just as the brilliant hues, red, \ellow, 

 or blue of many of the birds and insects of Ceylon 

 heighten the effect of the dark green foliage, so the coral 

 banks gain in beauty from contrast with the many- 

 coloured marine animals which frequent them. Such 

 are delicately variegated little crabs and fishes which seek 

 their food among the coral branches. Many of the 

 corals themselves are of gay and pleasing colours, e.g. 

 rose-red Procilloporas, red or yellow star coral, violet and 

 brown Heteroporae, and Madreporae, &c. Unfortunately, 

 these lovely colours are for the most part very fugitive, 



and disappear after a short exposure to the air. The 

 cilia and bright tentacula of the sensitive polypi are with- 

 drawn and concealed the instant the coral is disturbed, 

 and the whole becomes dull and colourless." 



" The eye which has been charmed by the brilliant 

 hues of the coral grove and its inhabitants is held spell- 

 bound by the beauty and variety of form revealed by 

 these animals. Each individual coral may well be com- 

 pared to a flower and each group of coral branches to a 

 plant, a tree, or a bush. Indeed, the belief that coral 

 was a vegetable growth was formerly universal, and it 

 was long before the idea of its animal origin gained 

 general acceptance. An entrancing and truly fairy-like 

 view of these marvellous coral banks may be had from a 

 boat during ebb tide, when the sea is calm. In the im- 

 mediate neighbourhood of the fort of Galle the water is 

 crystal clear, and so shallow that the keel of the boat 

 sometimes grates against the coral, and the outlines of 

 the branches can be distinguished even from the walls of 

 the fort above. A great variety of the most beautiful and 

 remarkable polypi are here comprised within a very small 

 space, and before many days were over I had amassed a 

 large collection." 



" Mr. Scott's garden, which he had kindly placed at my 

 disposal for drying purposes, presented a very- remarkable 

 appearance during the days of my stay at Queen's House. 

 The lovely tropical plants seemed to be competing for 

 the prize of beauty with the strange marine creatures 

 which had usurped their domain, and the delighted natu- 

 ralist wandered up and down feasting his eyes now on 

 the one and now on the other, uncertain as to which 

 should carry off the palm. It was impossible not to be 

 struck by the similarity in form between the polypi and 

 many of the garden plants ; and the orchids and spice 

 lilies were, in their turn, hardly distinguishable from 

 insects. It was as though the two great kingdoms of the 

 organic world intimated their desire to change places." 



" The majority of the coral which I collected in Galle 

 and afterwards in Belligemma was obtained by divers. 

 These I found quite as skilful and enduring as the Arabian 

 divers I had employed nine years before at Tur. Armed 

 with an iron stake they loosened large blocks of coral 

 from their foundation, and raised them with great dex- 

 terity into the boat. Many of the blocks weighed from 

 50 to So pounds, and it cost no little trouble and care to 

 deposit them safely. Some of the most beautiful varie- 

 ties are so brittle, that they break with their own weight 

 when taken out of the water, and cannot by any possi- 

 bility be preserved entire." 



" The full beauty of the coral banks cannot be seen from 

 above, even though the water be so shallow that the points 

 of coral scrape the keel of the boat. Not possessing a 

 diving-bell, I learnt with a little practice to swim to the 

 bottom with my eyes open, and most marvellous were then 

 the effects of the mystic green light in which the submarine 

 world was bathed, so different from the rosy light of the 

 upper air. The forms and movements of the swarms of 

 animals peopling the coral banks were doubly curious and 

 interesting thus seen." 



" A multitude of curious fishes, crabs, snails, mussels, 

 star-fish, &c, feed on the coral insect, upon which they 

 make their dwelling, and these coral eaters — which may 

 be classed among parasites — have acquired the most 

 abnormal forms and weapons of defence and aggression, 

 in the course of their adaptation to their peculiar mode of 

 life. But not without risk does the naturalist venture 

 among the coral groves. The Oceanidae, guardians of 

 the treasures of the deeD, warn off the rash intruder in a 

 thousand ways. The fire-coral {Millepora) and the 

 Medusa? swimming among them burn, when touched, like 

 the worst of stinging nettles, and the floating stings of 

 many Synanceja are as painful and dangerous as those of 

 the scorpion. Then the nip of crabs, large and small, is 

 a peril by no means to be despised. Black sea-urchins 



