THE article on my recent little book on “Mutations and Evolution” in NATURE of July 14, p. 636, shows such insight in the exposition of some of the views there set forth that it may seem ungrateful of me to venture to reply to anything the reviewer has written. Nevertheless, there is one important point in which I feel that my argument has been missed. My conceptions of the relation between recapitulatory and mutational characters are not easy to state clearly in a brief space, and I am willing to admit obscurity in certain passages, as evidenced by your reviewer's failure to grasp my meaning, but I am not willing to plead guilty to the more serious charge of obscurantism.