English prose literature; Exposition (Rhetoric); Readers -- Science
There are exceptions to this premature end; sometimes the two eggs
develop equally well; but such cases are exceptional, so that the
Bruchid family would be reduced to about half its dimensions if the
binary system were the rule. To the detriment of our peas and to the
advantage of the beetle, the eggs are commonly laid one by one and in
isolation.
A recent emergence is shown by a little sinuous ribbon-like mark, pale
or whitish, where the skin of the pod is raised and withered, which
starts from the egg and is the work of the newborn larva; a
sub-epidermic tunnel along which the grub works its way, while seeking a
point from which it can escape into a pea. This point once attained, the
larva, which is scarcely a twenty-fifth of an inch in length, and is
white with a black head, perforates the envelope and plunges into the
capacious hollow of the pod.
It has reached the peas and crawls upon the nearest. I have observed it
with the magnifier. Having explored the green globe, its new world, it
begins to sink a well perpendicularly into the sphere. I have often seen
it halfway in, wriggling its tail in the effort to work the quicker. In
a short time the grub disappears and is at home. The point of entry,
minute, but always easily recognizable by its brown coloration on the
pale green background of the pea, has no fixed location; it may be at
almost any point on the surface of the pea, but an exception is usually
made of the lower half; that is, the hemisphere whose pole is formed by
the supporting stem.
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.
Public-domain text, read in full here on John Shaqi.
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