At page 44 I wish you had enlarged a little on what you have said of the distinction between developmental and adaptive changes; for I cannot quite remember the point, and others will perhaps be in the same predicament.

I think I always saw that the larva and the adult might be separately modified to any extent.

Bearing in mind what strange changes of function parts undergo, with the intermediate state of use (244/3.
This slightly obscure phrase may be paraphrased, "the gradational stages being of service to the organism."), it seems to me that you speak rather too boldly on the impossibility of a mandibulate insect being converted into a sucking insect (244/4.

"There are, however, peculiar difficulties in those cases in which, as among the lepidoptera, the same species is mandibulate as a larva and suctorial as an embryo" (Lubbock, "Origin of Insects," page 423).); not that I in the least doubt the value of your explanation.
Cirripedes passing through what I have called a pupal state (244/5.
"Hence, the larva in this, its last stage, cannot eat; it may be called a "locomotive Pupa;" its whole organisation is apparently adapted for the one great end of finding a proper site for its attachment and final metamorphosis." ("A Monograph on the Sub-Class Cirripedia." By Charles Darwin.

London, Ray Soc., 1851.)) so far as their mouths are concerned, rather supports what you say at page 52.
At page 40 your remarks on the Argus pheasant (244/6.