Page:The Zoologist, 4th series, vol 5 (1901).djvu/365

are quite equal to those of a Frog.^[1] The Norwegian fishermen whitewash the rocks in the vicinity of their nets, or, where there are no rocks, erect white boards, or suspend sheets, which are termed "Salmon attractors," designed to represent the foam of the cataract, which the Salmon is seeking to ascend. But while the white colour is found attractive, the fishermen believe that the fish avoids red colours, so that red clothing is carefully discarded; and, according to Bishop Pontoppidan, even red tiles have been removed for this reason from a fisherman's house.^[2] Dr. S. Dixon, a president of the Pennsylvania Academy of Natural Sciences, in Philadelphia, had a large aquarium containing goldfish and other aquatic creatures, which he was in the habit of feeding every morning. During the winter, according to the 'New York Tribune,' he wore dark coloured clothing, and as soon as he approached the glass tank all the fish came to the surface of the water looking for crumbs. Changing his clothes to light-coloured fabrics the first day of May, the fish failed to recognize him, and went without food for two days. In fact, we cannot always conclude that the possession of eyes in some fishes is an indication of sight. According to Mr. Beddard, many deep-sea animals are totally blind; yet many species found in the deepest hollows of the ocean appear to have perfectly normal eyes. These discrepancies were partly accounted for by the theory of abyssal light. The histological study of the eyes of certain deep-sea Isopoda, particularly of Serolis and Arcturus, shows, however, that the appearance of well-developed eyes was often deceptive. Anyone, before having recourse to the microtome, would assert that the deep-sea Serolis neæva^[3] was as keen-eyed as any species of the genus. Yet sections through the eyes show that it is in a condition of degeneration; apart from the faceted cornea, there is but little of recognizable eye-structure left. In S. bromleyana the eyes are well-marked, but entirely devoid of pigment; no trace of optic tissue could be found by microscopical investigation. Mr. Beddard is therefore of opinion that there is no need of any theory of abyssal light; it is more likely that the state of preservation of the eyes is an index of the length of time that the species in question has been an inhabitant

1. 'Introd. Study Fishes,' p. 111.
2. Cf. Seeley, 'Freshwater Fishes of Europe,' p. 271.
3. Probably is meant: Serolis neaera Beddard 1884. (Wikisource-ed.)