THE PHYSIOLOGY OF DEEP-SEA LIFE. 309 



should be stung by large lasso-cells. According- to fishermen, 

 fishes avoid nets when filled with phosphorescent animals ; yet 

 on coral reefs fishes are constantly seen browsing upon the 

 corals and shoals of gorgonians. The commensalism of many 

 acalephs and quite delicate fishes living surrounded by the ten- 

 tacles of medusae, and especially by the intensely burning ten- 

 tacles of Physaliae, woidd seem to prove that they are not in 

 dread of lasso-cells. 



During the voyage of the " Challenger," Professor Moseley ^ 

 made a series of spectroscopic observations on the coloring-mat- 

 ters of various deep-sea invertebrates. Special attention was 

 paid to spectra presenting isolated bands, because they are read- 

 ily identified. He says : — 



'• Peculiar coloring-matters giving absorption spectra have now been 

 found to exist in members of all the seven groups of the animal king- 

 dom. Amongst Protozoa such coloring-matters occur in Infusoria and 

 Sponges ; amongst Coilenterata they occur both in Anthozoa and Hy- 

 dromedusae, in Echinodermata, in both Crinoidea, Eehinoidea, and 

 Holothuroidea, but not in the Asteroidea. In Vermes, in Annelids 

 and Gephyreans. In Arthropoda, in Crustacea and in Insecta. In 

 MoUusks, in Gasteropods only. In Vertebrata, in foiu- fish, three spe- 

 cies of Odax and one Labrichthys, and twelve birds of two closely 

 allied genera. The Echinodermata and Coelenterata ajDpear to be the 

 groups which are most prolific of such coloring-matters. Pentacriuin 

 and Antedonin seem to be widely diffused in immense quantities 

 through the tissues of the crinoids in which they occur ; and Echino- 

 derms generally seem to be characterized by the presence of evenly 

 diffused, abundant, and readily soluble pigments. 



" It seems improbable that the eyes of other animals are more per- 

 fect as spectroscopes 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 pigment in it. That the majority of spe- 

 cies of Antedon should have vivid coloring-matters of a simple charac- 

 ter, and that few or one only should be dyed by a very complex one, is 

 a remarkable fact, and it seems only possible 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 sul- 

 phate of copper is blue." 



Professor Moseley also observed that the phosphorescent light 



^ Quart. Jouru. Mic. Science, XVII., 1877, ii. 1. 



