8o THE POPULAR SCIENCE MONTHLY. 



seem to be nearly as many examples as there are living things. 

 The general cast of the plant and animals inhabiting it is a dull 

 brown. The goose barnacles, which are attached to the sprays in 

 great numbers, have white shell-cases with brown stalks. The 

 crabs are brown with usually a large white spot on their backs, 

 apparently in imitation of the barnacles, while many of the little 

 shrimps are marked in the same way. The spherical floats of the 

 sargassum are, furthermore, incrusted with the white lacelike 

 skeletons of bryozoa. The brown gulf weed is thus dappled with 

 white, and it is evidently advantageous for animals living in it to 

 simulate its colors, which they do in an extraordinary manner. 

 These colors are certainly protective, and if produced by the slow 

 process of natural selection, by which the hue of the organism 

 comes to harmonize with that of its environment, to the evident 

 advantage of the former, we must imagine this species of alga 

 to have floated about with these and similar animals for long ages. 



The salpas and medusae are beautifully phosphorescent at 

 night, and in fact most of the invertebrate life of the sea, which 

 on calm evenings swarms in myriads at the surface, possesses 

 this remarkable power. Then is every ripple followed by a train 

 of glowing sparks, every wave which breaks against the ship by 

 a brilliant meteoric shower. The larger medusae, which look like 

 softly glowing balls of mystic fire, and the barrel-shaped cteno- 

 phores are stars of the first magnitude, while behind there is a 

 whole galaxy of lesser lights, to count which would be much like 

 counting the stars. As I sat one evening watching our rudder, 

 after which trailed a long, curling line of sparks, four small fish 

 made their appearance and swam by the stern for several hours. 

 Their forms were illumined in the black water, and a train of fire 

 followed each as like little meteors they darted after the ship. 



We can form at most but a very imperfect idea of the life of 

 the sea from the chance glimpses afforded on the most favorable 

 voyage. We see but transient tokens of that vast life which the 

 sea holds in her teeming bosom. 



Could we project vertical sections of the ocean upon a screen 

 and examine these pictures in detail, what revelations might they 

 not unfold ! We would have the dwellers in every story of the 

 sea caught in their natural attitudes, the hosts of smaller ani- 

 mals at the surface, the many fish and other monsters of the 

 deep, and those far off dwellers in the abyssal sea. Scientific 

 study with the microscope, the tow-net, and deep-sea dredge is 

 revealing little by little those wonderful forms of life which have 

 been so long hidden from human eyes. 



