The genetic relationship of all vertebrates, from the earliest acrania and fishes up to the apes and man, is proved in its main lines by the concordant testimony of paleontology, comparative anatomy, and embryology. All competent and impartial zoologists now agree that the vertebrates are all descended from a _single_ stem, and that the root of this is to be sought in extinct pre-Silurian _Acrania_ (1), somewhat similar to the living lancelet. The _Cyclostoma_ (2) represent the transition from the latter to the _Fishes_ (3); and the _Dipneusts_ (4) the transition from these to the _Amphibia_ (5). From the latter have been developed the _Reptiles_ (6) on the one hand, and the _Mammals_ (7) on the other. The most important branch of this most advanced class is the _Primates_ (8); from the half-apes, or lemurs, a direct line leads, through the baboons, to the anthropoid apes, and through these on to man. (_Cf._ the tables on pp. 115-120). Further information will be found in chapters xxiv.-xxvii. of the _History of Creation_, and chapters xxi.-xxiii. of the _Evolution of Man_. PLATE I. [Illustration: GENEALOGICAL TREE OF THE VERTEBRATES] LAST WORDS ON EVOLUTION CHAPTER I THE CONTROVERSY ABOUT CREATION EVOLUTION AND DOGMA The controversy over the idea of evolution is a prominent feature in the mental life of the nineteenth century. It is true that a few great thinkers had spoken of a natural evolution of all things several thousand years ago. They had, indeed, partly investigated the laws that control the birth and death of the world, and the rise of the earth and its inhabitants; even the creation-stories and the myths of the older religions betray a partial influence of these evolutionary ideas. But it was not until the nineteenth century that the idea of evolution took definite shape and was scientifically grounded on various classes of evidence; and it was not until the last third of the century that it won general recognition. The intimate connection that was proved to exist between all branches of knowledge, once the continuity of historical development was realised, and the union of them all through the Monistic philosophy, are achievements of the last few decades.