Page:Popular Science Monthly Volume 63.djvu/42

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to be due to defective eyesight, for even though a moving worm were put in its immediate neighborhood, the fish did not appear to detect its presence through the sense of sight. At first, stimulated probably through its lateral line system, the fish seemed to feel the movements of the earthworm; it would then turn in the direction of the food, move towards it with apparently increasing enthusiasm, but when only at close range did it seem actually to see the prey. The fish's movements in feeding reminded one rather of a turtle than of a fish, or, best of all, of its kindred salamanders. Eyeing the moving worm steadily, it would make a sharp snap at it. If this movement failed, it would appear to deliberate, gaze fixedly at the object, and snap again. If more successful this time, it would pause with the food in its mouth, then with a series of accelerating snaps, the entire worm would be ingested. Occasionally a worm would be cut entirely in two by the quick snap of the fish's powerful jaws, and this would result in the

Fig. 7 a. Fig. 7 b. Fig. 7 c.

loss of the worm and in the feeding beginning anew. During this entire process the fish's arms would be spread widely apart, so as to support the weight of the head.

In later years the fish became quite tame, and would feed out of the hand of the laboratory attendant, who always maintained that the fish distinguished him from other visitors. Certain it was that he finally accustomed the fish to a diet of raw meat, and this substitute for earthworms proved a convenient one during the cold season. A finger thrust into the aquarium and stirred vigorously would be enough to attract the fish's rather sluggish attention: it would slowly leave its resting place, 'walk' toward the region of the disturbance, rise to the surface and after giving the usual evidence of bad eyesight would finally get its mouthful of food. The fecal material of the fish, one might mention, showed the cast of the spiral intestinal valve which in lung-fishes is almost as well developed as in sharks. Possibly, there-