Grant all races of man descended from one race--grant that all the structure of each race of man were perfectly known--grant that a perfect table of the descent of each race was perfectly known--grant all this, and then do you not think that most would prefer as the best classification, a genealogical one, even if it did occasionally put one race not quite so near to another, as it would have stood, if collocated by structure alone?
Generally, we may safely presume, that the resemblance of races and their pedigrees would go together.
I should like to hear what you would say on this purely theoretical case.
It might be asked why is development so all-potent in classification, as I fully admit it is?
I believe it is because it depends on, and best betrays, genealogical descent; but this is too large a point to enter on.
LETTER 205.

TO C.LYELL.Down, December 7th [1867].
I send by this post the article in the Victorian Institute with respect to frogs' spawn.

If you remember in your boyhood having ever tried to take a small portion out of the water, you will remember that it is most difficult.

I believe all the birds in the world might alight every day on the spawn of batrachians, and never transport a single ovum.

With respect to the young of molluscs, undoubtedly if the bird to which they were attached alighted on the sea, they would be instantly killed; but a land-bird would, I should think, never alight except under dire necessity from fatigue.