If the back of an earthworm be examined with a high-power lens (×500), small points of pigment will be seen here and there in its dorsal integument; these, I believe, are primitive eyes (ocelli). I think that the worm is enabled to tell the difference between light and darkness through the agency of these minute dark spots, which serve to arrest the rays of light, thus conveying a stimulus to nerve-fibrils, which, in turn, carry it to the sensorium. Any country schoolboy will tell you that worms can hear. He points to his simple experiment (pounding on the earth with a club) in proof of his assertion. For, as soon as he begins to pound the ground in a favorable neighborhood, the worms will come to the surface "to see what makes the noise." Darwin assumes that the worms feel the vibrations, which are disagreeable to them, and come to the surface in order to escape them. I do not deny the possibility or the probability of this assumption; I do deny, however, that it proves that worms are deaf. If the third anal segment (abdominal aspect) of a worm be examined, two round, disk-like organs incorporated in the integument will be found; these organs are supplied with special nerves which lead to the central nerve-cord. Experiments lead me to believe that these are organs of audition. When I tap the earth of my vermicularium with a pencil, the unmutilated worms will come to the surface; but, when the organs described above are removed, the worms so mutilated will not respond to the tapping, but will remain in their tunnel. The worms are not appreciably impaired by such mutilation; on the contrary, they seem to thrive as well as those to which the knife has not been applied. In creatures which possess, in all probability, the senses of touch, taste, smell, sight, and hearing, we would naturally expect to find some evidences of conscious determination; and we do. Certain leaves are the favorite food of earth-worms, while certain other leaves are eaten by them, but not with avidity. When these two kinds of leaves are given to worms, they will carefully select the favorite food and will ignore the other, thus unmistakably evincing conscious choice. Their avoidance of light is probably the result of conscious determination, and not reflex, as some observers maintain. Oysters taken from a bank never uncovered by the sea, open their shells, lose the water within, and soon die; but oysters kept in a reservoir and occasionally uncovered learn to keep their shells closed, and live much longer when taken out of the water. This is an act of intelligence due directly to experience without even the factor of heredity.[33] It is an instance of almost immediate adaptation to surrounding circumstances. [33] Dicquemase, _Journal de Physique_, Vol. XXVIII. p. 244; quoted also by Darwin, MS.; by Bingley, _Animal Biography_, Vol. III. p. 454; and by Romanes, _Animal Intelligence_, p. 25.