[63]

(44

to Ch 7

Metamorphosis & Embryology different - all this page confirms

In those animals, which according to our theoretical notions must have undergone very great modifications, it would appear probable that owing to successive modifications of every part of the structure becoming earlier & earlier developed in the embryo, at last all traces of a distinct embryonic form might be absorbed & lost

Prof. Owen (Lectures on Comparative Anatomy: invertebrate animals. 1855. p. 638) has remarked that in the Cephalopoda, the highest or most modified mollusca, & in the Arachnidæ considered by him the highest articulate, there is no distinct metamorphosis. But in the Acaridæ or Arachnidæ of extremely low development there is no great [illeg] of embryonic change can be detected, some other & quite distinct principle must come into play in accounting for the amount diversity & duration of embryonic changes. Many annelids offer a strong instance of great & little changes in form or metamorphosis in the same class. So again in certain pupiparous Flies, which I presume cannot be considered as having undergone modification in any extraordinary degree in comparison with other Diptera, Leon Dufour (Annal. des Sciences 3d Ser. Zoolog. Tom. 3 p. 749) could detect no trace of a larval stage.

[in margin:] But in all these cases there is probably connected metamorphosis