Page:Popular Science Monthly Volume 21.djvu/401

Rh over the retina-like membrane or the glandular follicles. The former kind of organs are considered by some naturalists true organs of vision (accessory eyes), the function of the latter being left unexplained by them."

There can hardly be a reasonable doubt that the functions of these organs, of both kinds, have reference to the conditions of light under which the animals live, but further than that judgment concerning them must be suspended. Dr. Günther briefly states three hypotheses that have been broached as possible: 1. That both kinds are "accessory eyes," to which the objection is offered that several fish having well-developed and even large eyes, perfectly adapted for seeing in the dark, are endowed with them, while in other deep-sea fishes, without external eyes, they are absent. 2. That only the organs with a lenticular body and a retina-like membrane behind it are visual, but that the glandular organs are phosphorescent; and more may be said for this view than for any other, since the glandular organs are certainly luminous. 3. That all the organs are producers of light, in which case it must proceed from the inner cavity and be emitted through the lens-like body as through a bull's-eye lantern. It will be hard to decide which of these suppositions is the right one, for it seems impossible to reproduce in the animals and their environment on the surface the conditions of an uninterrupted deep-sea life. [This subject was fully discussed by Dr. Ernest Krause in the last number of "The Popular Science Monthly."]

The deep-sea fishes display few colors. Their bodies are generally black or silvery, with a most brilliant sheen, which is preserved even after years of immersion in spirits. A few are "picked out" with bright scarlet, either on the fin-rays or the filaments attached to them. These filaments, it may be said, are eminently characteristic of fishes that inhabit still water, and the fact that many of the deep-sea forms are adorned with them perfectly accords with the belief that the abysmal regions are quiet.

Another remarkable property of some of these creatures is the possession of a stomach so capable of distention that it can hold a prey of twice or thrice the bulk of its destroyer. Dr. Günther gives figures of two or three fish with distended stomachs; and Mr. Johnson, his associate in this investigation, writes of a specimen which he procured at Madeira:

"The man from whom I obtained it stated that he had a fish with two heads, two mouths, four eyes, and a tail growing out of the middle of the back, which had astonished the whole market; and the fishermen, one and all, declared they had never met with anything like it before. At first sight it really did appear to be the monster described; but a short examination brought to light the fact that one fish had been swallowed by another, and that the features of the former were seen through the extensible skin of the latter. On extracting the fish that