spinneret projecting beyond it. Magnified. After Lyonet from Miall and
Denny's _Cockroach_.]

Such, in brief, is the course of the most familiar of insect
life-stories. For the student of the animal world as a whole, this
familiar transformation raises some startling problems, which have been
suggestively treated by F. Brauer (1869), L.C. Miall (1895), J. Lubbock
(1874), R. Heymons (1907), P. Deegener (1909) and other writers[2]. To
appreciate these problems is the first step towards learning the true
meaning of the transformation.

[2] The dates in brackets after authors' names will facilitate reference
to the Bibliography (pp. 124-8).

The butterfly's egg is absolutely and relatively of large size, and
contains a considerable amount of yolk. As a rule we find that young
animals hatched from such eggs resemble their parents rather closely and
pass through no marked changes during their lives. A chicken, a
crocodile, a dogfish, a cuttlefish, and a spider afford well-known
examples of this rule. Land-animals, generally, produce young which are
miniature copies of themselves, for example horses, dogs, and other
mammals, snails and slugs, scorpions and earthworms. On the other hand,
metamorphosis among animals is associated with eggs of small size, with
aquatic habit, and with relatively low zoological rank. The young of a
starfish, for example, has hardly a character in common with its parent,
while a marine segmented worm and an oyster, unlike enough when adult,
develop from closely similar larval forms. If we take a class of
animals, the Crustacea, nearly allied to insects, we find that its more
lowly members, such as 'water-fleas' and barnacles, pass through far
more striking changes than its higher groups, such as lobsters and