The reason why : $b a careful collection of many hundreds of reasons for things which, though generally believed, are imperfectly understood. A book of condensed scientific knowledge for the million
John Stuart Mill · en
deep_; yet a vascular system, which supplies nutrition, growth, and
life, to all of them together."
[Verse: "That which the palmer-worm hath left hath the locust eaten;
and that which the locust hath left hath the canker-worm eaten; and
that which the canker-worm hath left hath the caterpillar eaten."--JOEL
I.]
Lord Brougham, in a note upon the above, does not support Paley's
view. He says "It is more than probable that the parts which are to
appear in the perfect insect do _not_ exist in the larvæ, where there
is not much difference between the larva and pupa, excepting at the
time just previous to its becoming a pupa, at which time the larva is
motionless and torpid. The caterpillar of a moth, when about to turn
into a pupa, provides for the protection of the latter state, either by
surrounding itself with a web, or by some other means. Soon after this
is accomplished, the caterpillar becomes motionless, or nearly so; it
can neither eat nor crawl. At this time, and _not before_, the parts of
the pupa are forming within the skin of the caterpillar, which may be
easily seen by dissection."
It appears to the author, however, that Paley is partially right, and
Lord Brougham totally wrong, in these remarks. When Lord Brougham
asserts that the parts of the pupa are forming within the skin of
the caterpillar at that time when the transformation begins, "and
not before, which may be easily seen by dissection," he forgets,
that although in some instances it is the first moment when, to the
human eye, the organs of the new creature _become perceptible_, that
the "_three deep_" nature which Paley attributes to the _grub_, must
really have existed _in the egg_--that the _butterfly_ originated _in
the egg_, as certainly as did the _caterpillar_, or the _chrysalis_,
and that unless that egg had possessed its three mysterious embryos,
it would have been impossible for the grub to have progressed to
the stages of transformation. No one has ever known the embryo of a
bird's egg to pass through three distinct and dissimilar states of
existence; nor has any one ever known the embryo of the butterfly's
egg to stop short at either of the stages, if the proper conditions of
its existence and development were supplied to it. _Why?_ Because the
embryo of the insect has a _threefold_ nature, while that of the bird
is _single_.
[Verse: "They shall cut down her forest, saith the Lord, though it
cannot be searched; because they are more than the grasshoppers, and
are innumerable."--JEREMIAH XLVI.]
CHAPTER LXVI.
1292. _Why does the caterpillar become torpid when passing into the
state of the chrysalis?_