3. That “‘rudimentary structures’ also receive an explanation by means of this theory.
4. “That the singular facts of ‘homology’ are capable of a similar explanation.”
5. That “that remarkable series of changes which animals undergo before they attain their adult condition, which is called their process of development, and during which they more or less closely resemble other animals during the early stages of the same process, has also great light thrown on it from the same source.”
6. That “by this theory, and as yet by this alone, can any explanation be given of that extraordinary phenomenon which is metaphorically termed ‘mimicry.’”
To explain in detail the exact import of each of these heads would carry us beyond the limits of a magazine article; and the reader who wishes for more minute and definite information on them we must refer to Mivart’s own book, or to Darwin’s Origin of Species.
Pass we now to those facts which Darwin’s theory is incompetent to explain, and to the arguments against it. Mr. Mivart enumerates them thus:
1. “That ‘natural’ selection is incompetent to account for the incipient stages of useful structures.
2. “That it does not harmonize with the coexistence of closely similar structures of diverse origin.
3. “That there are grounds for thinking that specific differences may be developed suddenly instead of gradually.
4. “That the opinion that species have definite though very different limits to their variability is still tenable.