I had other schemes in view. I wished to learn how long this arrested life could be prolonged. A year after the hatching, I [[234]]examined my specimens again. This time I have gone too far. All the grubs are dead, reduced to dark brown granules; only those in the oak are alive and already well-grown. The experiment is conclusive; the Great Capricorn has the oak for her domain; any other tree is fatal to her grub.
Let us recapitulate these details, to which it were easy to add indefinitely. Among the vegetarian insects are some that are omnivorous, by which we mean that they are able to feed on a great variety of plants, but not on all indifferently: that goes without saying. These consumers of miscellaneous foodstuffs are in the minority. The others specialize, some more and others less strictly. One guest at the great banquet of the animal world requires a vegetable family, a group, a genus flavoured with certain alkaloids; another needs a given plant, sometimes faintly and sometimes highly flavoured; a third demands a seed, apart from which nothing is of use to it; and others require their pod, bud, or blossom, their bark, root or bough respectively. So it is with one and all. Each insect has its exclusive tastes, narrowly [[235]]limited, to the point of refusing the close equivalent of the thing accepted.
Lest we lose our way in the inextricable throng at the entomological banquet let us consider separately our two Capricorns, Cerambyx heros and C. cerdo. No two creatures could be more alike than these two long-horned Beetles; the lesser is the very picture of the greater. Let us also consider the three Saperdæ mentioned above. They are the same shape, as though they had been turned out of similar moulds, so much so that we should confound them if differences of size and above all of colour did not proclaim them to be of separate species.
The theorists tell us that our two Capricorns and their congeners spring from a common stock, ramified in various directions by the action of the centuries. In the same way, our three Saperdæ and the others are variations of a primitive type. The ancestors of the Capricorns, the Saperdæ and the Longicorns in general are in their turn descended from a remote precursor, who herself was descended from etc., etc. One more plunge into the darkness of the past and we [[236]]shall soon reach the origins of the zoological series. What begins at all? The Protozoon. How? With a drop of albumen. The whole succession of living creatures has gradually proceeded from this first clot of protoplasm.
As an effort of the imagination, this is magnificent. But the observable facts, which alone are worthy of admission to the stern records of science, the facts corroborated by experiment, cannot keep pace with the Protozoon. They tell us that, as food is the primordial factor of life, digestive capacities should be handed down by atavistic inheritance even more than are the length of the antennæ, the colour of the wing-cases and other details of quite secondary importance. To bring about the present state of affairs, in which the diet is so varied, the precursors must have eaten a little of everything. They ought to have bequeathed to their descendants an omnivorous regimen, which is a notable cause of prosperity.
A common origin would inevitably lead to a common diet. Instead of this, what do we see? Each species has its narrowly limited tastes, which have no reference to the tastes [[237]]of the cognate species. If they are related through a common ancestry, it is absolutely impossible to understand why, of our two Capricorns, one is allotted the oak and the other the hawthorn and the cherry-laurel; why, of our three Saperdæ, the first demands the black poplar, the second the elm and the third the dead cherry-tree. This gastric independence loudly proclaims independence of origin. And simple common sense, not always welcome to the adventurous theorists, is of the same opinion. [[238]]
[1] For the Pea-weevil and the Haricot-weevil, cf. The Life of the Weevil, by J. Henri Fabre, translated by Alexander Teixeira de Mattos: chaps. xi. to xiii.—Translator’s Note. [↑]
[2] For the Sloe-weevil, cf. idem: chap. x.—Translator’s Note. [↑]