It is precisely in this portion that the germ is found, which will not be eaten by the larva, and will remain capable of developing into a plant, in spite of the large aperture made by the emergence of the adult insect.  Why is this particular portion left untouched?  What are the motives that safeguard the germ?

It goes without saying that the Bruchus is not considering the gardener.  The pea is meant for it and for no one else.  In refusing the few bites that would lead to the death of the seed, it has no intention of limiting its destruction.  It abstains from other motives.

Let us remark that the peas touch laterally, and are pressed one against the other, so that the grub, when searching for a point of attack, cannot circulate at will.  Let us also note that the lower pole expands into the umbilical excrescence, which is less easy of perforation than those parts protected by the skin alone.  It is even possible that the umbilicum, whose organization differs from that of the rest of the pea, contains a peculiar sap that is distasteful to the little grub.

Such, doubtless, is the reason why the peas exploited by the Bruchus are still able to germinate.  They are damaged, but not dead, because the invasion was conducted from the free hemisphere, a portion less vulnerable and more easy of access.  Moreover, as the pea in its entirety is too large for a single grub to consume, the consumption is limited to the portion preferred by the consumer, and this portion is not the essential portion of the pea.

With other conditions, with very much smaller or very much larger seeds, we shall observe very different results.  If too small, the germ will perish, gnawed like the rest by the insufficiently provisioned inmate; if too large, the abundance of food will permit of several inmates.  Exploited in the absence of the pea, the cultivated vetch and the broad bean afford us an excellent example; the smaller seed, of which all but the skin is devoured, is left incapable of germination; but the large bean, even though it may have held a number of grubs, is still capable of sprouting.

Knowing that the pod always exhibits a number of eggs greatly in excess of the enclosed peas, and that each pea is the exclusive property of one grub, we naturally ask what becomes of the superfluous grubs.  Do they perish outside when the more precocious have one by one taken their places in their vegetable larder? or do they succumb to the intolerant teeth of the first occupants?  Neither explanation is correct.  Let us relate the facts.

On all old peas—­they are at this stage dry—­from which the adult Bruchus has emerged, leaving a large round hole of exit, the magnifying-glass will show a variable number of fine reddish punctuations, perforated in the centre.  What are these spots, of which I count five, six, and even more on a single pea?  It is impossible to be mistaken:  they are the points of entry of as many grubs.  Several grubs have entered the pea, but of the whole group only one has survived, fattened, and attained the adult age.  And the others?  We shall see.