English prose literature; Exposition (Rhetoric); Readers -- Science
Finally one of the excavators, favored by the direction taken, attains
the central portion. It establishes itself there, and all is over; the
others have only to die. How are they warned that the place is taken? Do
they hear their brother gnawing at the walls of his lodging? can they
feel the vibration set up by his nibbling mandibles? Something of the
kind must happen, for from that moment they make no attempt to burrow
further. Without struggling against the fortunate winner, without
seeking to dislodge him, those which are beaten in the race give
themselves up to death. I admire this candid resignation on the part of
the departed.
Another condition--that of space--is also present as a factor. The pea
weevil is the largest of our Bruchidae. When it attains the adult
stage, it requires a certain amplitude of lodging, which the other
weevils do not require in the same degree. A pea provides it with a
sufficiently spacious cell; nevertheless, the cohabitation of two in one
pea would be impossible; there would be no room, even were the two to
put up with a certain discomfort. Hence the necessity of an inevitable
decimation, which will suppress all the competitors save one.
Now the superior volume of the broad bean, which is almost as much
beloved by the weevil as the pea, can lodge a considerable community,
and the solitary can live as a cenobite. Without encroaching on the
domain of their neighbors, five or six or more can find room in the one
bean.
Moreover, each grub can find its infant diet; that is, that layer which,
remote from the surface, hardens only gradually and remains full of sap
until a comparatively late period. This inner layer represents the crumb
of a loaf, the rest of the bean being the crust.
In a pea, a sphere of much less capacity, it occupies the central
portion; a limited point at which the grub develops, and lacking which
it perishes; but in the bean it lines the wide adjoining faces of the
two flattened cotyledons. No matter where the point of attack is made,
the grub has only to bore straight down when it quickly reaches the
softer tissues. What is the result? I have counted the eggs adhering to
a bean-pod and the beans included in the pod, and comparing the two
figures I find that there is plenty of room for the whole family at the
rate of five or six dwellers in each bean. No superfluous larvae perish
of hunger when barely issued from the egg; all have their share of the
ample provision; all live and prosper. The abundance of food balances
the prodigal fertility of the mother.
If the Bruchus were always to adopt the broad bean for the establishment
of her family, I could well understand the exuberant allowance of eggs
to one pod; a rich foodstuff easily obtained evokes a large batch of
eggs. But the case of the pea perplexes me. By what aberration does the
mother abandon her children to starvation on this totally insufficient
vegetable? Why so many grubs to each pea when one pea is sufficient only
for one grub?
Public-domain text, read in full here on John Shaqi.
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