CONCEALMENT AND COLORS IN CRUSTACEA—MINKIEWICZ. 481 
the experiments made in 1906, in which I obtained the same colors 
in Hippolyte with varied intensities of lighting, in small crystallizing 
pans wrapped in fine colored papers. This method is a little too 
primitive, but it was the only one that I was able to employ. 
4°, There exist Hippolytes very ill adapted to change (within a 
week or more). But if they do alter their color, it is only after the 
molt* that the change appears, either in part or totally. This 
proves that the molting is not merely an external process, but a 
process which affects all the tissues while increasing their plasticity. 
5°. Once changed, the color of the Hippolyte, even in the most 
obstinate, becomes plastic and can be changed with astonishing 
rapidity, sometimes in ten minutes. 
The fact is most interesting to me, because it demonstrates the 
part that habit (in the purely physiological meaning of the word) 
may have; that is to say, the use or the want of use of an organ (as 
Lamarck has said) in the formation of the permanent varieties of an 
animal primitively polychromatic. 
Thus the ideas of Lamarck, often derided, again take the place that 
is their due. 
Now the chromatic varieties of Hippolyte are developed only in- 
dividually, without being hereditary. 
And since each of these diversely colored individuals has, according 
to the observations of Keeble and Gamble, its corresponding specific 
chromotropism, it is evident that in acquiring its coloration it acquires 
simultaneously its synchromatic chromotropism. 
Color and chromotropism are here intimately connected; they are 
always synchromatic with the color of the environment, under the 
direct action of which they develop each time by a sort of resonance 
of the entire organism, as well as of its chromatophores and its 
“retina” as of its neuro-muscular apparatus. It is impossible for 
me to concern myself here with the question of this chromo-kinetic 
resonance, to which I shall devote a special chapter in my next work. 
T have wished only to insist upon this constant parallelism of variable 
color with variable chromotropism. 
It would be most important and interesting to study by the experi- 
mental method the progressive steps in the changes in these two 
phenomena; to try to establish whether these changes are absolutely 
simultaneous or whether they follow each other in time, the parallel- 
ism being then only the definite stage of the physiological process. 
This is a problem to tempt a biologist, and one which, I believe, 
it is not impossible to solve. 
It is certain, from my researches, that the power to effect changes 
of color diminishes with the prolonged failure to exercise the chro- 
4@The molting of Hippolyte, as of many other Crustacea, occurs habitually 
during the night. 
