Experience of artificial fertilization such as is affected with ornamental plants in order to obtain new variations in color, has led to the experiments, the {206} details of which I am about to discuss. The striking regularity with which the same hybrid forms always reappeared whenever fertilization took place between the same species, induced further experiments to be undertaken, the object of which was to follow up the developments of the hybrid in a number of successive generations of their progeny. Those who survey the work that has been done in this department up to the present time will arrive at the conviction that among all the numerous experiments made not one has been carried out to such an extent and in such a way as to make it possible to determine the number of different forms under which the offspring of hybrids appear, or to arrange these forms with certainty, according to their separate generations, or to ascertain definitely their statistical relations. These three primary necessities for the solution of the problem of heredity--namely, first, the number of different forms under which the offspring of hybrids appear; secondly, the arrangement of these forms, with definiteness and certainty, as regards their relations in the separate generation; and thirdly, the statistical results of the hybridization of the plants in successive generations, are the secret of the success of Mendel's work, as has been very well said by Bateson, in commenting on this paragraph in his work on Mendel's "Principles of Heredity." This was the first time that any one had ever realized exactly the nature of the problems presented in, their naked simplicity. "To see a problem well is more than half to solve it," and this proved to be the case with Mendel's straightforward vision of the nature of the experiments required for advance in our knowledge of heredity. {207} While Mendel was beginning his experiments almost absolutely under the guidance of his own scientific spirit, and undertaking his series of observations in the monastery garden without any reference to other work in this line, he knew very well what distinguished botanists were doing in this line and was by no means presumptuously following a study of the deepest of nature's problems without knowing what others had accomplished in the matter in recent years. In the second paragraph of his introduction he quotes the men whose work in this science was attracting attention, and says that to this object numerous careful observers, such a Kölreuter, Gärtner, Herbert, Lecoq, Wichura and others, had devoted a part of their lives with inexhaustible perseverance. To quote Mendel's own words:--