As soon as the female bee deposits her eggs on the surface of the
honey stored in the cells, the larvae of the Sitaris leap on the eggs and
devour them. Afterwards they undergo a complete change; their eyes
disappear; their legs and antennae become rudimentary, and they feed on
honey; so that they now more closely resemble the ordinary larvae of
insects; ultimately they undergo a further transformation, and finally
emerge as the perfect beetle. Now, if an insect, undergoing
transformations like those of the Sitaris, were to become the progenitor of
a whole new class of insects, the course of development of the new class
would be widely different from that of our existing insects; and the first
larval stage certainly would not represent the former condition of any
adult and ancient form.
On the other hand it is highly probable that with many animals the
embryonic or larval stages show us, more or less completely, the condition
of the progenitor of the whole group in its adult state. In the great
class of the Crustacea, forms wonderfully distinct from each other, namely,
suctorial parasites, cirripedes, entomostraca, and even the malacostraca,
appear at first as larvae under the nauplius-form; and as these larvae live
and feed in the open sea, and are not adapted for any peculiar habits of
life, and from other reasons assigned by Fritz Muller, it is probable that
at some very remote period an independent adult animal, resembling the
Nauplius, existed, and subsequently produced, along several divergent lines
of descent, the above-named great Crustacean groups.
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