DEEP SEA LIFE IN THE BAY OF BENGAL. 549 
tion where eyes ought to be, there are indeed the rudiments of eyes, showing 
that it is descended from ancestors that had eyes, but it itself, living in dark- 
ness, is quite blind ; it has no need foreyes, eyes would be liable to be injured, 
and are therefore a disadvantage, and so they have been gradually eliminated 
by natural selection. These crustaceans, Polycheles, Nophropeis, and Lyreidus, 
are also blind. They have eye-stalks, like their close relatives the lobsters, 
but the eye-stalks, like those of Cambarus, carry no eyes. It commonly hap- 
pens that the absence of eyes is compensated by the development of organs 
of touch—just as a blind man feels his way about witha stick. This beauti- 
ful specimen of Bathypterozs illustrates this compensatory development : its 
eyes are not quite lost, but they are quite rudimentary, and in compensation 
the fin-rays are enormously prolonged, and are abundantly supplied with 
nerves, On the other hand there may occur, and there actually does occur, 
another line of development equally interesting, and perhaps even more wonder- 
ful, Animals may become adapted to darkness by becoming blind—sur- 
rendering at once, so to speak, to the irresistible force of their environment 
like Tauredophidium, &c., &c. Other forms, however, when deprived of sun- 
light, may meet the difficulty by manufacturing their own light, just as man 
when deprived of sunlight by the daily rotation of the earth manufactures fire 
sticks and candles. There is nothing really out of the way in animals thus 
developing light by the combustion of their own tissues. The familiar fire- 
fly is a daily illustration of this common physiological phenomenon. In the 
fire-fly certain cells situated on a certain part of the abdomen undergo chemical 
changes which result in phosphorescence—the albumen of these cells is burnt 
or oxidized, it is converted into uric acid, and urates, with the evolution of 
light, just as the muscles of other animals are burnt and converted into urates 
and urea, &c., with the evolution of heat and mechanical motion. Again it is 
well known to all voyagers by sea that most marine animals are at times 
luminous. Now in certain deep sea animals living in constant darkness, this 
luminosity is very highly developed. Cells in particular regions of the body 
become aggregated to form glands, the secretion of which is brilliantly lumin- 
ous. These fishes, Thawmastormias, Gonostoma, and Leptoderma, illustrate this, 
as also do these crustaceans, Nephrops, Aristaeus, and Heterocarpus. In this case 
the eyes, instead of aborting, are very singularly developed, being of enormous 
size, like those of owls, to catch all the comparatively feeble light of their own 
manufacture. These illustrations, then, must suffice to show some of the 
modifications of structure imposed by the peculiar conditions of life at the 
bottom of the ocean. 
Let us next consider some of the modifications which follow from the 
action of the law “ kill and eat,” a law which acts with peculiar rigour in the 
depths of the sea, because there are no plants there, and carnivorism is a 
universal rule. If there are no plants, how is the cycle of life carried on? 
On dry land we know that plants are the great manufactures manufacturing 
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