CONCEALMENT AND COLORS IN CRUSTACEA—MINKIEWICZ. 475 
Now, the animal is decidedly positively erythrotropic (+) and at 
the same time negatively janthinotropic (—). The result is, it seems 
to me, sufficiently conclusive. 
But I have ascertained facts much more suggestive, drawn from 
numerous experiments that I made during these last years, very 
varied experiments, bearing upon the most dissimilar animals (Ante- 
dons, Nemerteans, Daphniids, Phronimas Dromiids, Pagurids, larvee 
of Saccocirrus and of Crustacea, etc.), and concerning both the action 
of incidental light coming from the prismatic spectrum or from col- 
ored glass, and the action of light reflected by screens and by colored 
backgrounds. 
It would be superfluous and inconsistent with the aim of this article 
to dwell too long on the question of chromotropism and to give a de- 
tailed description of all my results. 
I shall select only what is necessary to find the data in the succes- 
sive development of my analysis. Among all these results there are 
two which are of chief importance to the problem which occupies us. 
The first is, that 
ge i W | reen 
it is not only direct 
colored light which 
ait! 
gi a 
mal is placed. I 
hws. for? iex- + 
produces its specific 
tropic action, but also 
ample, Lineus Pu- Fic. 8.—Diagram showing the chromotropism of the 
: Pagurids. 
daylight reflected 
by colored surfaces 
on which the ani- 
Blue 
Violet 
ber, an _ erythro- 
tropic animal, becomes motionless in diffused daylight on the red 
floor of a small aquarium the bottom of which is divided into two 
parts differently colored, or, in the absence of red, on the yellow, 
green, etc., always on the background which has the color nearest to 
red and avoids the one the color of which is nearest violet, the condi- 
tions of lighting being identical. 
The second result is the autonomy of the phenomena of chromo- 
tropism and their functional independence of ordinary phototropism 
(with relation to daylight). 
One of the best pr oofs in this matter is furnished us by the case of 
the Pagurids. It is to be remarked that each animal requires par- 
ticular conditions in order to manifest its chromotropic pecularities. 
Those conditions must be ascertained or no results will be fortheom- 
ing in regard to the present question. Thus the Pagurids (Bern- 
hardus prideauxti, B. cuanensis, B. striatus, etc.) manifest their 
chromotropism only when placed on the bottom of an aquarium of 
