This, beyond a doubt, is the secret of the peas exploited by the Bruchus and yet remaining fit to sprout. They are injured but not dead, because they are invaded in the free hemisphere, [[195]]the part which is at the same time easier to enter and less easy to wound. Moreover, as the whole pea is too much for a single grub, the loss of substance is reduced to the piece preferred by the consumer; and this piece is not the essential part of the pea.
Given other conditions, with seeds either very small or exceedingly large, we should see the results changing entirely. In the first case, the germ would be gnawed like the remainder and would perish by the tooth of the too niggardly served grub; in the second case, the abundant food would allow of several guests. The common vetch and the broad bean, exploited in the absence of the pea, tell us something in this connection; the smaller seed, devoured all but the skin, is a ruin whose germination we may expect in vain; the larger, on the contrary, despite the Weevil’s numerous cells, is still capable of sprouting.
Admitting that the number of eggs on the pod is always much greater than that of the peas contained, and that, on the other hand, each pea is the exclusive property of one grub, we wonder what becomes of the surplus. Do these larvæ perish outside, when the more precocious have taken their places one by one in the leguminous larder? Do they succumb to the intolerant teeth of the early occupants? They do neither. Let us set forth the facts.
On all old peas, now dry, from which the adult [[196]]Weevil has issued, leaving a gaping hole, the magnifying-glass reveals a varying number of fine, reddish-brown dots, perforated at the centre. What are these spots, of which I count five or six or even more on a single pea? There is no mistake possible: they are the entrance-points of so many grubs. Several workers have therefore penetrated into the seed; and of the whole gang only one has survived, waxed big and fat and attained the adult age. And the others? We shall see.
At the end of May and in June, during the laying-season, inspect the still green and tender peas. Nearly all the seeds invaded show us the multiple dots which we already observed on the dry peas abandoned by the Weevils. Does this actually mean an assembly of guests? Yes. Skin the aforesaid seeds, separate the seed-lobes, subdivide them if necessary. We discover several larvæ, very young, bent into a bow, fat and wriggling, each in a little round hollow in the heart of the victuals.
Peace and comfort seem to reign in the community. There is no quarrelling, no jealous competition among neighbours. The eating has begun, provisions are plentiful and the banqueters are separated from one another by partitions formed by the as yet untouched portions of the seed-lobes. With this isolation in separate cells, there is no fear of squabbles; the guests will not bite one another, by accident or intention. All the occupants [[197]]enjoy the same rights of property, the same appetite and the same strength. What will be the end of the communal working?
I split some peas which I have found to be well-stocked and place them in a glass tube. I add others daily. This method keeps me informed of the boarders’ progress. At first there is nothing special. Isolated in its narrow recess, each grub nibbles around itself and eats frugally and peacefully. It is still quite small; a speck of food surfeits it. Nevertheless, a dish consisting of one pea cannot satisfy so large a number until the end. Famine threatens; all save one must die.
Soon indeed the aspect of things changes. One of the grubs, the one occupying the central position in the pea, grows faster than the others. He has hardly begun to be larger than his competitors when these cease to eat and refrain from digging any farther. They lie motionless and resigned; they die the gentle death which reaps unconscious lives. They disappear, wasted away to nothing. They were so tiny, the poor victims! Henceforth the whole pea belongs to the sole survivor. But what has happened, to produce this desolation around the privileged one? For lack of a relevant answer, I will propound a suggestion.
In the centre of the pea, more gently stewed than the rest by the sun’s chemistry, may there not be an infant-pap, a pulp of a quality better-suited to the delicate organs of a grub? Here [[198]]perhaps, stimulated by tender, highly flavoured and sweeter food, the stomach becomes more vigorous and fit to cope with food less easily digested. A baby is fed on milk before it receives the basin of broth and the bread of the able-bodied. Might not the central portion of the pea be the Weevil-grub’s feeding-bottle?
Fired by one ambition and endowed with equal rights, all the occupants of the seed set out towards the delicious morsel. It is a laborious journey; and frequent halts are made in temporary recesses. The grubs rest; pending better things to come, they frugally crunch the ripe substance around them; they gnaw even more to open a way than to fill their stomachs.