THE GRUB’S SENSATIONS
Though the Capricorn-grub possesses these useless legs, the germs of future limbs, there is no sign of the [[214]]eyes with which the fully-developed insect will be richly gifted. The larva has not the least trace of any organs of sight. What would it do with sight, in the murky thickness of a tree-trunk? Hearing is likewise absent. In the untroubled silence of the oak’s inmost heart the sense of hearing would be superfluous. Where sounds are lacking, of what use is the faculty of discerning them?
To make the matter certain I carried out some experiments. If split lengthwise the grub’s abode becomes a half-tunnel, in which I can watch the occupant’s doings. When left alone it alternately works for a while, gnawing at its gallery, and rests for awhile, fixed by its pads to the two sides of the tunnel. I took advantage of these moments of rest to inquire into its power of hearing. The banging of hard bodies, the ring of metallic objects, the grating of a file upon a saw, were tried in vain. The animal remained impassive: not a wince, not a movement of the skin, no sign of awakened attention. I succeeded no better when I scratched the wood near it with a hard point, to imitate the sound of some other grub at work in its neighbourhood. The indifference to my noisy tricks could be no greater in a lifeless object. The animal is deaf.
Can it smell? Everything tells us that it cannot. Scent is of assistance in the search for food. But the Capricorn-grub need not go in quest of eatables. It [[215]]feeds on its home; it lives on the wood that gives it shelter. Nevertheless I tested it. In a log of fresh cypress wood I made a groove of the same width as that of the natural galleries, and I placed the grub inside it. Cypress wood is strongly scented; it has the smell characteristic of most of the pine family. This resinous scent, so strange to a grub that lives always in oak, ought to vex it, to trouble it; and it should show its displeasure by some kind of commotion, some attempt to get away. It did nothing of the kind: once it had found the right position in the groove it went to the end, as far as it could go, and made no further movement. Then I set before it, in its usual channel, a piece of camphor. Again no effect. Camphor was followed by naphthaline. Still no result. I do not think I am going too far when I deny the creature a sense of smell.
Taste is there no doubt. But such taste! The food is without variety: oak, for three years at a stretch, and nothing else. What can the grub’s palate find to enjoy in this monotonous fare? The agreeable sensation of a fresh piece, oozing with sap; the uninteresting flavour of an over-dry piece. These, probably, are the only changes in the meal.
There remains the sense of touch, the universal passive sense common to all live flesh that quivers under the goad of pain. The Capricorn-grub, therefore, is limited to two senses, those of taste and touch, and both of these [[216]]it possesses only in a very small degree. It is very little better off than Condillac’s statue. The imaginary being created by the philosopher had one sense only, that of smell, equal in delicacy to our own; the real being, the oak-eater has two, which are inferior even when put together to the one sense of the statue. The latter plainly perceived the scent of a rose, and clearly distinguished it from any other.
A vain wish has often come to me in my dreams: to be able to think, for a few minutes, with the brain of my Dog, or to see the world with the eyes of a Gnat. How things would change in appearance! But they would change much more if understood only with the intellect of the grub. What has that incomplete creature learnt through its senses of touch and taste? Very little; almost nothing. It knows that the best bits of wood have a special kind of flavour, and that the sides of a passage, when not carefully smoothed, are painful to the skin. This is the limit of its wisdom. In comparison with this, the statue with the sensitive nostrils was a marvel of knowledge. It remembered, compared, judged, and reasoned. Can the Capricorn-grub remember? Can it reason? I described it a little time ago as a bit of intestine that crawls about. This description gives an answer to these questions. The grub has the sensations of a bit of intestine, no more and no less. [[217]]