Asks whether LJ can throw light on this subject: "What are the checks and what the periods of life by which the increase of any given species is limited?" CD has been driven to conclude that species are mutable; allied species are co-descendants from common stocks.

On checks to increase of species and the observations which led him to regard species as mutable in form. Would welcome "at some future time" LJ’s criticism of the "sketch" of his conclusions.