4 THE ZOOLOGIST. 



inhabit tubes, and it was the brilliant luminosity of these that 

 led, in 1870, to doubts as to the correctness of the views enter- 

 tained by the distinguished naturalists of the ' Porcupine ' Expe- 

 ditions, and especially by the late Sir Wyville Thomson, viz. 

 that this attribute served the two diverse purposes of attracting 

 prey or of alluring enemies. The naturalists of the 'Porcupine' 

 were struck by the phosphorescence of many of the forms living 

 at great depths in the Atlantic, such as Alcyonarians, Brittle- 

 stars, and Annelids. In some places the mud itself was full of 

 luminous specks. Accordingly, they broached the idea that the 

 abyssal regions might depend for light solely on their phos- 

 phorescent inhabitants. Moreover, since the young of certain 

 Star-fishes are more luminous than the adults, it is probable 

 that this is part of the general plan which provides an enormous 

 excess of the young of many species, apparently as a supply of 

 food, their wholesale destruction being necessary for the due 

 restriction of the multiplication of the species, while the breeding 

 individuals are provided with special appliances for escape or 

 defence. For example, a young Hyas araneus, having dense tufts 

 of a phosphorescent zoophyte waving from its shell and limbs, 

 must, on the one hand, like an Indian beauty with her fireflies, 

 be the cynosure of all (predatory) eyes ; and, on the other, be 

 enabled to throw such a flood of light on the food-question as to 

 distance many rivals. This view, however, had long been known 

 to naturalists. Thus Dr. Coldstream, in Todd's 'Cyclopasdia,' 

 observes: — "Considering that in the ocean there is absolute 

 darkness at 800 or 1000 feet (133 to 166 fathoms), at least that 

 at such depths the light of the sun ceases to be transmitted, 

 Macculloch has suggested that, in marine animals, their lumin- 

 ousness may be a substitute for the light of the sun, and may be 

 the means of enabling them to discover one another, as well as 

 their prey. It seems to be particularly brilliant in those inferior 

 animals which from their astonishing powers of reproduction, 

 and from a state of feeling apparently little superior to that of 

 vegetables, appear to have been in a great measure created for 

 the supply and food of the more perfect kinds." 



If, as the ' Porcupine ' naturalists say, luminosity subserves 

 the purpose of guiding animals to their prey, or of causing them 

 to be preyed upon (an unfortunate result), or even of illuminating 



