As we begin the twentieth century, the most interesting question in biology is undoubtedly that of heredity. Just at the dawn of the century three distinguished scientists, working in different countries, rediscovered a law with regard to heredity which promises to be even more important for the science of biology in the twentieth century than was Lamarck's work for the nineteenth century. This law, which, it is thought, will do more to simplify the problems of heredity than all the observations and theories of nineteenth-century workers, and which has already done much more to point out the methods by which observation, and the lines along which experimentation shall be best directed so as to replace elaborate but untrustworthy scientific theorizing by definite knowledge, was discovered by a member of a small religious community in the little-known town of Brünn, in Austria, some thirty-five years before the beginning of the present century.
Considering how generally, in English-speaking countries at least, it is supposed that the training of a clergyman and particularly that of a religious unfits him for any such initiative in science, Father Mendel's discovery comes with all the more emphatic surprise. There is no doubt, however, in the minds of many of the most prominent present-day workers in biology that his [{197}] discoveries are of a ground-breaking character that will furnish substantial foundation for a new development of scientific knowledge with regard to heredity.
Lest it should be thought that perhaps there is a tendency to make Father Mendel's discovery appear more important here than it really is, because of his station in life, it seems desirable to quote some recent authoritative expressions of opinion with regard to the value of his observations and the importance of the law he enunciated, as well as the principle which he considered to be the explanation of that law.
In the February number of Harper's Monthly for 1903, Professor Thomas Hunt Morgan, Professor of Biology at Bryn Mawr, and one of the best known of our American biologists, whose recent work on "Regeneration" has attracted favorable notice all over the world, calls attention to the revolutionary character of Mendel's discovery. He considers that recent demonstrations of the mathematical truth of Mendel's Law absolutely confirm Mendel's original observations, and the movement thus initiated, in Professor Morgan's eyes, gives the final coup de grace to the theory of natural selection. "If," he says, "we reject Darwin's theory of natural selection as an explanation of evolution, we have at least a new and promising outlook in another direction and are in a position to answer the oft-heard but unscientific query of those who must cling to some dogma: if you reject Darwin, what better have you to offer?"
Professor Edmund B. Wilson, the Director of the Zoological Laboratory of Columbia University, called attention in Science (19 December, 1902) to the fact that studies in cytology, that is to say, observations on the formation, development, and maturation of cells, confirm Mendel's principles of inheritance and thus furnish another proof of the truth of these principles.
Two students working in Professor Wilson's laboratory have obtained definite evidence in favor of the cytological explanation of Mendel's principles, and have thus made an important step in the solution of one of the important fundamental mysteries of cell development in the very early life of organisms.
In a paper read before the American Academy of Arts and Sciences last year, Professor W. E. Castle, of Harvard University, said with regard to Mendel's Law of Heredity:--
What will doubtless rank as one of the greatest discoveries in the study of biology, and in the study of heredity, perhaps the greatest, was made by Gregor Mendel, an Austrian monk, in the garden of his cloister, some forty years ago. The discovery was announced in the proceedings of a fairly well-known scientific society, but seems to have attracted little attention, and to have been soon forgotten. The Darwinian theory then occupied the centre of the scientific stage, and Mendel's brilliant discovery was all but unnoticed for a third of a century. Meanwhile, the discussion aroused by Weissman's germ plasm theory, in particular the idea of the non-inheritance of acquired characters, put the scientific public into a more receptive frame of mind. Mendel's law was rediscovered [{199}] independently by three different botanists, engaged in the study of plant hybrids--de Vries, Correns, and Tschermak, in the year 1900. It remained, however, for a zoologist, Bateson, two years later, to point out the full importance and the wide applicability of the law. Since then the Mendelian discoveries have attracted the attention of biologists generally. [Footnote 15]
[Footnote 15: This paper was originally published in part in the Proceedings of the American Academy of Arts and Sciences, Vol. xxxviii, No. 18, January, 1903. It may be found complete in Science for 25 September, 1903.]