ABSTRACT
This chapter discusses some of the difficulties and objections which may be urged against the author's theory. It shows how cautious people should be in concluding that the most different habits of life could not graduate into each other; that a bat, for instance, could not have been formed by natural selection from an animal which at first could only glide through the air. The chapter examines that a species may under new conditions of life change its habits; or have diversified habits, with some habits very unlike those of its nearest congeners. On the theory of natural selection, people can clearly understand the full meaning of that old canon in Natural History, Natura non facit saltum. This canon, if people look only to the present inhabitants of the world, is not strictly correct; but if they include all those of past times, it must by the author's theory be strictly true.
