Januaey 22, 1904.] 



SCIENCE. 



137 



Brown-Goode as to such an explanation of 

 protective coloration in fishes. "On cer- 

 tain ledges along the coast of New England 

 are rocks covered by dense growths of scar- 

 let and crimson seaweeds. The codfish, the 

 cunner, the sea raven, the rock eel, and the 

 wrymouth, which inhabit these brilliant 

 groves, are all colored to match their sur- 

 roundings; the cod, which has naturally 

 the lighter color, being most brilliant in 

 its scarlet hues, while others whose skins 

 have a large and original supply of black 

 have deeper tints or dark red and brown. ' ' 

 He then quotes farther the suggestions of 

 Goode that these colors are due to pigment 

 derived either directly or indirectly, from 

 the red algse; those which are carnivorous 

 feeding upon the Crustacea and other ma- 

 rine organisms whose stomachs are full of 

 the algse and their pigments which pass 

 unchanged into the tissues of the fishes. 



He also quotes a similar conclusion of 

 Giinther as to the origin of the red pig- 

 ment of the salmon being derived from the 

 red pigment of the Crustacea upon which it 

 feeds. "While admitting that in the cases 

 just cited there has been no attempt at 

 demonstration of the proposed explana- 

 tion, it yet would seem highly probable. 

 "It is too remarkable a coincidence that 

 the fish normally with but little pigment 

 should when among these weeds be bright 

 red, and that the fish normally possessing 

 black pigment should be dark red, to per- 

 mit of a settlement of the question off- 

 hand by the easy help of natural selection 

 —without at least some further inquiry." 



With the foregoing considerations con- 

 cerning the general origin and develop- 

 ment of pigments and their relations to the 

 colors of organisms, we may next proceed 

 to pass rapidly in review such groups of 

 animals as we may choose to consider, and 

 may institute a brief inquiry as to the sig- 

 nificance of their types of coloration as 

 factors of adaptation. 



With the avowed purpose of restricting 

 my observations and discussion as far as 

 practicable to the lower groups of inver- 

 tebrates as already announced, it will 

 suffice to say further that in justification- 

 of such a course I am constrained to con- 

 sider the lower animals, particularly 

 coelenterates, as more favorable subjects 

 from which to obtain fundamental conclu- 

 sions than are the more highly specialized 

 insects or birds which have had so large a 

 measure of attention in earlier investiga- 

 tions along these lines. 



Furthermore, it seems highly probable 

 that future investigations will involve 

 more of direct experimentation than has 

 hitherto been the case, and if so, these 

 lower series will naturally afford some of 

 the best material available for such in- 

 quiries, not only because of the more 

 ready and rapid responses obtained, but 

 from the relative simplicity of their organ- 

 ization and the consequent simplicity of 

 results likely to be obtained in each ease. 



If further warrant were demanded for 

 a comparatively limited survey, or special 

 emphasis upon a limited group of animals, 

 I should find it in a measure in the per- 

 sonal interest and familiarity which has 

 come from special researches connected 

 therewith. 



Beginning with the hydrozoa it may be 

 noted in the outset that though including 

 the simplest of the Coelenterates we shall 

 find a remarkable- variety and range of col- 

 oration. Among the hydroids, as is well 

 known, coloration is neither very remark- 

 able as to brilliance nor distribution. 

 Many, if not most, are almost without 

 color distinction, except in the dull brown- 

 ish or amber colors found in such as 

 Obelia, Halecium, and other campanula- 

 rians. This may be due in part to the fact 

 that the colonies are so generally encased 

 within a chitinous perisarc which, while 

 somewhat colored as already indicated, is 



