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Page:Popular Science Monthly Volume 26.djvu/379

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PROTECTIVE MIMICRY IN MARINE LIFE.

In the gloom of the garden the color would not be noticed, though the profuseness of the sweat, as its falling proved, might; furthermore, if it had been blood it would have left stains, if not crusts or coagula behind it, and excited still further notice and remark. From all these considerations I think we have reason enough to conclude that this case of bloody sweat exists only in the affectionate and pious fancy of the Church—come down to us from the former ages, when men would rather believe than examine, and left undisturbed even to these times, when, alas! men would, as a rule, rather examine than believe.

 

PROTECTIVE MIMICRY IN MARINE LIFE.
By Dr. WILHELM BREITENBACH.

BY mimicry we understand the assumption by animals of a deceptive similarity answering a protective purpose, not only to other animals, but also to lifeless objects, and, in color, to the surroundings. In a biological application, this definition of the term, though different from the common one, is well founded; for similarity of an animal with any object affords it protection, by enabling it to approach its prey unobserved; by facilitating its escape from enemies; or by shielding it, under cover of its resemblance to unpleasant objects, from hostile attacks. A number of observations have been published, by various well-known authors, upon the interesting phenomena of mimicry, but they have related generally to land animals, while the cases of the occurrence of similar phenomena among the inhabitants of the sea have been less extensively noticed. A few have been mentioned by Haeckel and Carus Stern, but I have others, of not less high interest, to describe.

On my voyage from Brazil to England in July, August, and September, 1883, I had many opportunities to secure and examine closely specimens of pelagic life. From the 30th of August to the 5th of September, we crossed the Sargasso Sea, between latitude 25° 12' and 34° 39', and longitude 33° 52' and 35° 52' west. The sea-weeds were not massed in extensive fields, but were distributed in single groups of larger or smaller size, and these were driven by the wind in nearly straight lines, that could be followed with the eye to considerable distances. The linear arrangement was also made distinct to me by its pelagic life, particularly by its great colonies of radiolaria, or polycyttaria, salpæ, and other orders. Thus, I find in my notes such items as, "September 3d, polycyttaria in colossal masses, thick, wide bands of them stretching along for miles; September 14th, immense masses of little salpæ and polycyttaria, causing the water to display milky bands."

I did not neglect to fish up masses of the Sargasso sea-weed every