the second
larval stage, which is oval in form, and not segmented, the primitive
band is formed.
In concluding the account of his remarkable discoveries, Ganin draws
attention to the great differences in the formation of the eggs and the
germs of these parasites from what occurs in other insects. The egg has
no nutritive cells; the formation of the primitive band, usually the
first indication of the germ, is retarded till the second larval stage
is attained; and the embryonal membrane is not homologous with the
so-called "amnion" of other insects, but may possibly be compared with
the skin developed on the upper side of the low, worm-like acarian,
Pentastomum, and the "larval skin" of the embryos of many low Crustacea.
He says, also, that we cannot, perhaps, find the homologues of the
provisional organs of the larvae, such as the singularly shaped antennae,
the claw-like mandibles, the tongue-or ear-like appendages, in other
Arthropoda (insects and Crustacea); but that they may be found in the
parasitic Lernaean crustaceans, and in the leeches, such as Histriobella.
He is also struck by the similarity in the development of these
egg-parasites to that of a kind of leech (Nephelis), the embryo of which
is provided with ciliae, recalling the larva of Teleas (Fig. 197 _B_,
_C_), while in the true leeches (Hirudo) the primitive band is not
developed until after they have passed through a provisional larval
stage.
This complicated metamorphosis of the egg-parasites, Ganin also compares
to the so-called "hyper-metamorphosis" of certain insects (Meloe,
Sitaris, and the Stylopidae) made known by Siebold, Newport and Fabre,
and he considers it to be of the same nature.
He also, in closing, compares such early larval forms as those given in
figures 193 _E_ and 194, to the free swimming Copepoda. Finally, he says
a few words on the theory of evolution, and remarks "there is no doubt
that, if a solution of the questions arising concerning the genealogical
relations of different animals among themselves is possible, comparative
embryology will afford the first and truest principles." He modestly
suggests that the facts presented in his paper will widen our views on
the genetic relations of the insects to other animals, and refers to the
opinion first expressed by Fritz Mueller (Fuer Darwin, p. 91), and
endorsed by Haeckel in his "Generelle Morphologie," that we must seek for
the ancestors of insects and Arachnida in the Zoea fo
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