Grant and Ferson and Harker--we were known to scientists across half the world. It was Grant, of course, the eldest of us, who was best known. A tall, saturnine-faced and dark-browed Scotsman, his utter and undivided passion for research was a byword among us. It used to be said, though not in his hearing, that Grant would have vivisected his own grandmother if he thought some new principle might be learned by it. All respected the man, or the man's achievements, but he never had a tithe of the popularity that was Ferson's. Ferson was in fact a complete contrast to his superior, a short-statured man of middle age with unruly hair and beard and warm brown, friendly eyes. As for myself, the third of the trio, I had neither the brilliant scientific mind of Grant nor the keen vision of Ferson, but by dint of ceaseless plodding with monotonous details, I had built for myself a reputation that linked my name with theirs. Aside from our professorial duties in the university's lecture-rooms, we had each of us our separate work. I was plodding away with my dull experiments on cell-grouping, which I expected would some day yield a theory that would astound all cytologists. Now and then I received help on some difficult point from Ferson, who was himself immersed in an attempt to demolish the Snelsen-Morrs re-vertebration theory by prying into the interior structure of innumerable unheard-of lizards. Grant, however, never received or gave any help, keeping his work entirely to himself. We had gathered, from his rare references to it, that he had been working for months on one of the broader problems of evolutionary science, but that was all we knew, and we were as amazed as any when Grant published the statement that touched off the sensational "evolution controversy." It is needless for me to give here all the details of the thing. It is sufficient to say that Grant, in his statement, announced that he had solved at last the greatest enigma of biological science--that he had discovered the cause of evolution. One can understand what an uproar that statement created, and was bound to create. For the cause of evolutionary change has always been the supreme problem of biology. Long ago Darwin and Wallace and Lamarck and their fellows had laid the processes of evolution bare. They had shown to an astonished world that life on earth was not static in forms that had always existed and always would exist, but that it was in constant change and movement up through constantly changing forms. The eohippus had changed, had evolved into the horse, and in future ages would be something different still. The great felines that had roamed earth had evolved into smaller forms and into tame cats. A certain branch of ape-like forms had evolved into great hairy troglodytes and then into modern men. All life on earth was constantly changing, evolving, forced ever upward through the diverging channels of evolution into new and different forms.