22 
H. N. MOSELEY. 
product, and of no use to the animal, although, of course, 
in some instances it has been turned to account for sexual 
purposes, and may have other uses occasionally. There is 
no reason why a constant emission of light should be more 
beneficial than a constant emission of heat, such as takes 
place in our own bodies, and it is quite conceivable that 
animals might exist to which obscure heat-rays might he 
visible, and to which, therefore, men and mammals generally 
would appear constantly luminous. 
However, be the light beneficial to them or not, it seems 
certain that the deep sea must be lighted here and there by 
greater or smaller patches of luminous Alcyonarians, with 
wide intervals, probably, of total darkness intervening. Very 
possibly the animals with eyes congregate around these 
sources of light. 
The phosphorescent light emitted by three species of deep- 
sea Alcyonarians was examined with the spectroscope and 
found to consist of red, yellow, and green rays only. Hence, 
were the light in the deep sea derived from this source, in the 
absence of blue and violet light, only red, yellow, and green 
colours could be effective. No blue animals were obtained in 
deep water, hut blue animals are not common elsewhere. It is 
remarkable that almost all the deep-sea shrimps and schizo- 
pods, which were obtained in very.great abundance, are of an 
intense bright scarlet colour, differing markedly in their in¬ 
tensity of colour from shallow-water forms, and having 
apparently for some purpose developed an unusually large 
quantity of the same red pigment matter which colours small 
surface Crustacea. 
A brilliant green colouring matter was found in some deep- 
sea Annelids. 
No doubt in many cases the colouring of the deep-sea 
animals, as in the case of the purple Ilolothurians, is useless 
and only a case of persistence. The madder colouring of 
some of the soft parts of the Corals may be in like case, hut 
possibly useful for attraction of prey, being visible by the phos¬ 
phorescent light. Nearly all, if not all, of the fish certainly 
living on the bottom in the deep sea were of a dull black or 
quite white and semi-transparent. 
I regret much that I did not examine deep-sea fish with 
regard to the existence and amount of haemoglobin to be found 
in them. 
The same colouring matters exist in deep-sea animals which 
are found in shallow-water forms. Polyperythrin is found 
abundantly in surface-swimming Rhizostomae and in deep-sea 
Corals and Actiniae. Antedonin occurs in a shallow water 
