PROTECTIVE MIMICRY IN MARINE LIFE. 365 



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. 



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PROTECTIVE MIMICRY m MARINE LIFE. 



By De. WILHELM BEEITENBACH. 



BY mimicry we understand the assumption by animals of a decep- 

 tive 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 men- 

 tioned 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 Sep- 

 tember, 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 dis- 

 tances. The linear arrangement was also made distinct to me by its 

 pelagic life, particularly by its great colonies of radiolaria, or polycyt- 

 taria, salpse, 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 salpae and polycyttaria, causing the water to display milky bands." 



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



