138 



SCIENCE. 



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



seldom if ever of any considerable brill- 

 iance or diversity. Among the tubula- 

 rians, in many of which the development 

 of a perisarc is slight, and always lacking 

 over the hydranth itself, there is often 

 found considerable coloration, as in Eu- 

 dendriuni, Pennaria, Corymorpha and 

 others. And in these color is usually 

 found associated more particularly with 

 the development of the sexual products, 

 or during the season of reproductive activ- 

 ity, which is a matter of considerable sig- 

 nificance, to be taken up in a later con- 

 nection. 



As is well known, the predominance of 

 alternation of generations in these animals 

 brings into prominence the sexual phase, 

 which in most species is an independent 

 organism— the medusa. And it is in con- 

 nection with the medusse that we find the 

 most marked development of color. There 

 does not, however, appear to be any well- 

 defined distribution of colors into patterns. 

 Among the Hydromedusee the distribution 

 of pigment, which is almost the only con- 

 spicuous kind of color present, is chiefly 

 in association with the gonads, the tissues 

 of the stomach and the regions of the chy- 

 miferous canals, though in some cases also 

 extending to the tentacles and in the re- 

 gions of the sensory organs. It should not 

 be overlooked, however, that in many of 

 these medusas the color tints are among the 

 most beautiful and delicate known, though 

 lacking the intensity more common among 

 the Scyphomedusse and corals. 



Turning attention to the Seyphomedusee 

 we find as just suggested a more copious 

 development of color, and also what is 

 more significant, in many cases its distri- 

 bution into something like definite pat- 

 terns, as is more or less evident in such 

 genera as Cyanea, Pelagia and Rhizostoma. 

 It is, however, no less evident that among 

 these we have, as in the former, the deposi- 

 tion of pigment along the lines of most 



active metabolism, such as the gastrovas- 

 cular and reproductive organs, in most 

 abundance and usually of greatest bril- 

 liance. 



It is, however, when we come to the An- 

 thozoa, which includes the corals, acti- 

 nians, sea-fans, etc., that we find the cli- 

 max of coloration, both as regards bril- 

 liance and intensity. To look into the 

 crystalline depths of the waters about a 

 coral reef where these varied forms thrive 

 in great garden-like areas is to gaze upon 

 a scene, the fairy-like features of which it 

 would be difficult to exaggerate. Here are 

 actinians, corals, sea-fans, sea-feathers, 

 etc., which abound in the richest profusion 

 and endless variety, seeming to vie with 

 each other in the effort to produce the most 

 exquisite displays of every tint of the spec- 

 trum. 



In the distribution of color there is not 

 apparently any advance as to differentia- 

 tion over that found in the Scyphomedusse, 

 if indeed as much, though among the actin- 

 ians certain stripings and mottlings occur 

 over the exterior of the body. It is worthy 

 of note that in those forms in which the 

 tendency toward definite coloration is more 

 evident there appears to be in many cases 

 considerable variation of coloration. This 

 is particularly noticeable in such forms as 

 Metridium and Cyanea. 



Face to face with this rich profusion 

 and beauty of color what is its signifi- 

 cance? How has it originated and what 

 does it mean? Is it simply the expression 

 of some original constitution, peculiar to 

 the entire class, and if so why does it differ 

 in so marked a degree among the different 

 subclasses? We may safely dismiss such 

 an alternative as altogether unnecessary 

 and without value as an explanation. May 

 it be considered as an adaptation to pro- 

 tection, the result of natural selection? 

 Certainly in no direct sense, for -without 

 exception, so far as I am aware, the more 



