542 W. H. LONGLEY 



ousness of which it remains antagonistic, it is difficult to avoid 

 the conclusion, that, no matter how glaring the colors with which 

 it is £vssociated, its presence is constructive evidence of the 

 concealing function of the coloration observed. 



Color change 



Color change in fishes has been studied extensively by phys- 

 iologists and histologists.2 Much has been learned regarding 

 the mechajiism which produces and controls it. It has also 

 been shown, in a few cases, that its general effect is to assimilate 

 the organism with its environment. Yet the observed facts 

 are not adequate tests of the hypotheses which postulate con- 

 spicuousness; for the changes that have been most fully investi- 

 gated occur rather slowly in fishes whose hues are not particularly 

 gaudy, and with no known exception have been induced in 

 artificial environments. But, granted that an animaFs ability 

 to change its color under laboratory conditions is demonstrated, 

 in every case it remains to be seen whether when they occur in 

 nature its color changes conform to the same or other laws. It 

 is then for the first time possible to estimate their probable 

 effect in diminishing visibility, warning off enemies, or otherwise 

 advancing the interest of the individual that displays them. 



Concerning the color changes of fishes in their natural habitat 

 few facts are available. It is known that the trout, for example, 

 may exhibit a dark or light phase according to the character 

 of its haunts, but no statement of the rate at which one may 

 succeed the other has been encountered. Knowledge upon 

 this point seems to differ only in degree from that we have re- 

 garding Bodianus fulvus and punctatus, which have been con- 

 sidered by systematists different subspecies or species. The 

 two forms described have been observed, however, by C. Tate 

 Regan ('09) in the New York aquarium, and by the writer, upon 

 the reefs in Porto Rico, to be merely alternative color phases of 

 one creature, which may replace one another instantaneously. 



Other cases comparable with these may be gleaned from the 

 literature. Gourret ('93) describes the color varieties of the 



2 For a review of the literature of the subject see van Rynberk ('06). 



