« НазадПродовжити »
at his prey, and as quickly return. The station which he occupies in this manner is invariably well chosen. Should a favourite haunt where food is concentrated by the current be rather crowded by his fellows, he will prefer contending with them for a share in it, to residing long in an unproductive locality.
A Trout will chiefly frequent one place during all the summer months. It is well known that he quits the larger waters, and ascends the smaller brooks for the purpose of spawning in October and November, when the male assists the female in making a hole in the gravel wherein to deposit the ova. By some it is supposed, that they both lie dormant in the mud during the greatest severity of the winter.
Sense of Hearing. In order that we might be enabled to ascertain the truth of a common assertion, (viz.) that fish can hear voices in conversation on the banks of a stream, my friend, the Rev. Mr. Brown, of Gratwich, and myself, selected for close observation a Trout poised about six inches deep in the water, whilst a third gentleman, who was situated behind the fishing-house, (i. e.) diametrically opposite to the side where the fish was, fired off one barrel of his gun. The possibility of the flash being seen by the fish was thus
wholly prevented, and the report produced not the slightest apparent effect upon him.
The second barrel was then fired; still he remained immovable; evincing not the slightest symptom of having heard the report. This experiment was often repeated, and precisely si. milar results were invariably obtained; neither could I, or other persons, ever awaken symptoms of alarm in fishes near the hut by shouting to them in the loudest tones, although our distance from them sometimes did not exceed six feet. The experiments were not repeated so often that they could become habituated to the sound, if heard.
It is possible that fishes may be in some manner affected by vibrations communicated to their element, either directly, or by the intervention of aerial pulsations ; although it does not seem to be clearly proved that they possess any organ appropriated exclusively to the purpose of hearing. At all events, it appears that neither the above-mentioned explosions, nor the loud voices, had power to produce vibrations or undulations in the water, which could so affect them.
Leaving the discussion of this intricate subject to more able and learned speculators, we will deem it sufficient for us to know that the abovementioned Trout had no ears to hear either the voices or the gun; and I firmly believe, that the zest which friendly chat often imparts to the exercise of our captivating art, need never be marred by an apprehension that sport will be impaired thereby.
Of all the senses in fish, sight is perhaps that which is of most importance to them. Their eyes are of course well adapted to the element they inhabit ; indeed their subsistence seems to depend mainly upon the great sensibility of the optic nerve, and the just adaptation of the crystalline and other humours to their proper office.
A fish can perhaps frequently distinguish much more of objects which are out of his own element than it is often imagined that he can.
When Mr. A. B. (fig. 1. plate 2.), for instance, situated upon a certain eminence at a given distance from a fish, C, which is near the bottom of the water, looks over the edge of a bank, D, in the direction A F Z, he might (if unacquainted with the laws of refraction) imagine, that neither the fish C, nor any other fish below the line of his direct vision, AF Z, could see him; whereas C could see A B by means of the pencil of light, AFCE B, bent, or refracted at the surface of the water, E F, and the image of A B would appear in the eye of the fish shortened and transferred to G H. The fish, in fact, could see the whole of the man, round, or over the corner of the bank, by the aid of the water above C, if both were situated as respectively represented in the diagram ; but if the surface of the water should be at I K, (i. e.) about as low as the fish's eye, then he could not see any part of the figure AB, because a straight or unrefracted pencil of light, A CB, would be obstructed by the bank.
Increased obliquity in pencils of light falling from an object upon a surface of water, is accompanied by still more rapidly increasing refraction : but the distinctness with which the object is seen decreases in an inverse proportion.
The bending or refraction which a pencil of light, as NEOFM (fig. 2.), falling very obliquely upon the surface of the water, undergoes before arriving at the eye of a fish, at 0, is sufficient to produce very great indistinctness and distortion of the image of M P formed in his eye.
Perhaps indistinctness of vision may, on other accounts, also take place in the eye of a fish looking through air. The crystalline and various other humours may not be capable of such comprehensive adjustment as would enable him to see so distinctly through air as he can through water.
But long before a pencil of light, as N E L, becomes horizontal, it will not enter the water at