144 



SCIENCE. 



[N. S. Vol. XIX. No. 473. 



eration of which it is impossible to enter 

 here. There is a matter, however, which 

 I can not ignore in connection with the 

 group, namely, the rather remarkable fact 

 that in two phyla having so little in com- 

 mon as to habit, structure or environment, 

 there should be so striking a color resem- 

 blance. This is further heightened by the 

 fact that while one is a prey to almost 

 every denizen of the sea of predatory 

 habit, the other is almost correspondingly 

 exempt. So far as I know echinoderms 

 have few enemies, and are of course 

 largely invulnerable against such as might 

 otherwise find palatable feeding among 

 these sluggish herds. If the color is in the 

 one case protective, why not in the other f 

 Or if it be not protective on the other 

 hand, why claim such in the first? That 

 sexual selection might have some place 

 among Crustacea may not seem improbable. 

 But if color is its signal here what does it 

 imply among echinoderms, where in the 

 nature of the case it must be ruled out of 

 account 1 



Discussing the significance of colors 

 among the echinoderms Mosely submits 

 the following interesting problem: "Those 

 coloring matters which, like those at pres- 

 ent under consideration, absorb certain 

 isolated areas of the visible spectrum, must 

 be considered as more complex, as pig- 

 ments, than those which merely absorb 

 more or less of the ends of the spectrum. 

 * * * It seems improbable that the eyes 

 of other animals are more perfect as spec- 

 troscopes than our own, and hence we are 

 at a loss for an explanation on grounds of 

 direct benefit to the species of the exist- 

 ence of the peculiar complex pigments in 

 it. That the majority of species of Ante- 

 don should have vivid coloring matters of 

 a simple character, and that few or only 

 one should be dyed by a very complex one, 

 is a remarkable fact, and it seems only pos- 

 sible to say in regard to such facts that the 



formation of the particular pigment in the 

 animal is accidental, i. e., no more to be 

 explained than such facts as that sulphate 

 of copper is blue." 



Considered from the standpoint of met- 

 abolism such facts would hardly seem to 

 assume the difficulty which might be im- 

 plied in the case just cited, indeed they are 

 in perfect alignment with what might be 

 anticipated, and what has in cases pre- 

 viously cited been found to be actually 

 occurring. 



Similar conditions as to color and color 

 significance are also matters of common 

 knowledge in relation to moUusca. Per- 

 haps few groups among animals exhibit 

 more brilliant and varied colors than are 

 to be found among gasteropods, yet in 

 many of them this factor can have no 

 more value as a means of adaptation than 

 do biliary pigments or haemoglobin among 

 vertebrates, where as pigments their sig- 

 nificance is nil. Of them, Darwin, with 

 his usual frankness, has said, as previously 

 cited, 'These colors do not appear to be 

 of any use as a protection; they are prob- 

 ably the direct result, as in the lowest 

 classes, of the nature of the tissues — the 

 patterns and the sculpture of the shell de- 

 pending on its manner of growth.' Ee- 

 ferring in the same connection to the 

 bright and varied colors of nudibranchs, 

 he further declares, "many brightly col- 

 ored, white, or otherwise conspicuous spe- 

 cies, do not seek concealment ; whilst again 

 some equally conspicuous species, as well 

 as other dull colored kinds, live under 

 stones and in dark recesses. So that with 

 these nudibranch molluscs, color appar- 

 ently does not stand in any close relation 

 to the nature of the place which they in- 

 habit." 



Into the classic shades afforded by the 

 insects as a fruitful haunt and stronghold 

 of natural selection I must not venture. 

 Not that its problems have all been solved, 



