THE COLORS OF WATER. 255 



to southern seas are unable to say enough of the splendid colors 

 conjured up by the coral reefs. 



But even this is not all. All lakes and seas swarm with swim- 

 ming or " pelagic " plants and animals. Green and yellow, one- 

 celled, microscopic algse are exceedingly common to a consider- 

 able depth; and green and yellow algse sometimes come to the 

 front in such masses that " the Red Sea " becomes no arbitrary 

 designation, but the correct expression of an observed fact. I 

 have seen the bay of Villafranca colored partly red by millions 

 of swimming Anchinia rubra about as large as peas ; I have seen 

 mile-long strips, several metres broad, immediately along the 

 shore on the Riviera, colored a deep royal blue by compressed 

 masses of swimming salleemans (Veletta spirans). 



We can not absolve the transparent swimming water-organ- 

 isms, from the larger medusa down to the infinitesimal microbes, 

 from having a certain amount of influence on the color of water. 

 We should not be able to see their crystal-clear bodies if they 

 did not refract the rays of light in a different direction from the 

 surrounding water. By this means they send out a multitude 

 of refracted rays, which singly are of little importance, but in 

 the aggregate must produce an effect through their accumulation 

 when millions of these living beings are crowded into a cubic 

 millimetre. To what purpose should we have in some parts of 

 the retina of our eye a million of sensitive elements or rods to 

 the square millimetre, if we could not seize single impressions 

 and unite them into a view of the whole ? 



Finally, we will not forget the air that is mixed with the 

 water. If we shake a viscous fluid in the air, it becomes whitish, 

 and at last white, like milk. Yet the fluid and the air are both 

 transparent. But the air-bubbles scattered through the water 

 refract the light in another way. The wave looks whitish, quite 

 white on its edges, from the inclosed air, and as the motion grows 

 stronger the white becomes more prominent, with a greenish tone 

 when the water is clear and the sky clouded, radiant yellow in 

 sunshine, and clay-yellow when the water is not clear. All these 

 tones mix with the colors of the deep, and with the mirror-colors 

 of the surface. Thus the question of the causes of the colors of 

 water rises to be one of the most complex problems of science as 

 well as of art, the full solution of which has not yet been reached, 

 in spite of the various efforts of men of science and of pictorial 

 artists, because in order to meet the apprehension of the common 

 eye they have to continue into a picture the endlessly changing 

 colors and shapeless figures which the sea affords. But when I 

 stand before a wave painted by Mazure in Paris (he is there usu- 

 ally called Mazure le Vague, the Wave-Mazure), and see how that 

 artist, without help of shore, walls, buildings, or ships, which sup- 



