CONCEALMENT AND COLORS IN CRUSTACEA—MINKIEWICZ. 471 
because all the striking finality of the instinct in question is only 
apparent, as we shall see immediately. 
§ 3. OBSERVATIONS APPARENTLY CONTRADICTORY. 
There are plenty of these facts, and they are not the negative or 
indistinct results mentioned above; on the contrary, they are most 
clear and absolutely positive. I will select from them these three: 
The first, which I have already quoted from the observations of 
H. Fol, is that the crabs place on their backs objects which make 
them still more visible than they were before. 
Secondly, in spite of H. Fol’s observation that “ when the vegetable 
covering has increased to the point of becoming cumbersome it tears 
it bit by bit with one of its pairs of feet (always with its claws! 
R. M.), cleans itself thoroughly, and then proceeds to stick on its 
carapace ”’—in spite of that—I say—the crabs, covered with one 
color, when transferred to an aquarium of another color, even the 
most discordant, from what I have been able to observe, never re- 
move their old costume. ‘They hang new papers beside the old ones 
in sufficient quantity to fill the unoccupied space. 
Lastly and most important: In the black aquarium the crabs never 
take black paper if they find any other color. They cover them- 
selves with green, red, or white, making a bright patch on the black 
floor of the aquarium, instead of concealing themselves. 
How can these strange errors of so perfect an instinct of so-called 
mimetism be accounted for? Can facts recurring constantly under 
definite conditions be considered, as is usually done, as errors of 
instinct ? 
It will be said, perhaps, that we have here a case of terrification, 
of warning colors, to use Wallace’s term, or aposemathic colors accord- 
ing to Poulton. But is it possible that under the conditions of ex- 
periment the self-disguising animals transform themselves in a 
moment into terrifying animals? 
Is it not more logical to seek some other explanation? Is it not 
possible to penetrate by careful analysis the ultimate significance of 
these actions, and to find a scientific explanation by which these 
will be shown neither as exceptional or contradictory occurrences, 
nor as normal teleology of instinct, but as a resultant of the physi- 
ological determinism of instinctive actions? This is what I shall 
try to bring out in what follows. 
IV. BLINDED CRABS. 
I found it impossible successfully to blind the crabs by covering 
their corneze with asphaltum or any other black substance, as the 
claws of Maja are too mobile and quick; I therefore cut the ocular 
peduncles. i comecun ie 
45745°—sm 190931 
