Page:Popular Science Monthly Volume 66.djvu/211

Rh This is more likely to happen if the forces of natural or artificial selection were in its favor. There are many cases where the variant in minor points is prepotent and outweighs the original stock. Monstrosities produced by crossing often perpetuate themselves as well as the species does."

"One difficulty with the mutation theory of Dr. De Vries, in my opinion, is lack of sufficiently wide experimentation. Fuller investigations will certainly show that the 'sports' or 'chance' variations come under the same law as that of 'fluctuating' variations, mutations being only fluctuating variations carried beyond the critical point where past fluctuating variations can not withstand the accumulated forces without disintegration, thus bending them in a new direction."

"Professor Hubrecht is certainly in error in stating that the mean fluctuations can not be carried into the extreme or 'sport' variations by selection. Professor Hubrecht speaks of two divergent processes, 'fluctuating variations' and 'mutations' which he says: 'Darwin has not sufficiently kept separate.' They are not separate; one is only a tendency toward the other, and which continued, though latent, may, or will, at last become dominant, so as to swing the fluctuating variations fully out of the old orbit into the 'mutation' or 'sport' condition. Radical changes of environment for a series of generations will produce a tendency to sport, but hybridization will bring it about far more abruptly, and for practical plant or animal breeding or for scientific study of all these variations, far more satisfactorily."

" The misunderstanding evidently comes from not having a clear knowledge of latent and dominant hereditary forces. A knowledge of these explains the whole matter and makes harmony between Darwin and Wallace, leaving Professor De Vries's careful experiments good, but coming to different conclusions on the results."

"Professor Hubrecht also states that 'now for the first time—forty years after the appearance of the 'Origin of Species'—the actual birth of a species has been observed by him.' As I have produced several good species by hybridization, as good as nature herself has produced, and as others have done the same by selection alone, the above sentence is hardly true. But as before stated, hybridization followed by selection is the shortest plan by which valid new species can be produced. In other words, the 'period of mutation' can he produced at will!"

"The mutation theory of the origin of species seems like a step backward towards the special creation theory, and without any facts as yet adequate to support it as a universal theory, however valuable and suggestive the experiments of Dr. De Vries may be."

"There is a remarkably close analogy between hybridization and grafting. Bringing. over from France a prunus (P. mirobolana var.