ABSTRACT
In the case of most of the higher animals, the development of the embryo goes on within the body of the mother until it becomes a highly complex organism, composed of many tissues and organs. In the case of the birds, this development takes place within the egg, which is outside the body of the mother. When the general facts of embryonic development were made known about a hundred years ago, those who were inclined toward the evolution theory pointed out the facts of parallelism as very significant. It was claimed that one of the higher animals in its embryonic development always passes through a very rapid and very much condensed recapitulation of the history which its species has passed through in the course of its evolution through a long series of gradually developing ancestors. Adam Sedgwick will admit that there is a general correspondence between the developing embryo and the evolutionary history of the race.
