Page:Popular Science Monthly Volume 56.djvu/299

Rh has sufficed for the particular purposes of the physicist. Of course, only a little corner of the universe has been explored, but in the study of non-living matter we have come to no impassable gulfs, no chasms across which we can not throw bridges of hypothesis. Does the method equally suffice when it is applied to living matter? Can we give a purely physical account of such matter? Do we make any attempt to apply the physical method to describe and explain those motions of matter which on the psychical view we term voluntary? In practice the strictest physicist abandons the physical view, and replaces it by the psychical. He admits the study of purpose as well as the study of motion, and has to confess that here the physical method of prediction fails.

Honors to Sullivant and Lesquereux.—"Sullivant day," August 22d, was devoted in the American Association to the commemoration of the lives and works of William S. Sullivant and C. Leo Lesquereux, botanists, the former distinguished for his studies in the mosses and the latter for his researches in paleobotany, both of whom lived and did the work by which they became famous in Columbus, Ohio. Sullivant was born and passed the whole of his life in Columbus. Lesquereux, a Swiss by birth, lived in Columbus during many of his most fruitful years, and worked alongside of Sullivant. A considerable number of objects associated with the two botanists were on exhibition—rare botanical specimens, charts and pictures connected with their labors, and complete sets of their published works—and excellent and highly prized portraits of them were shown. The families of both were represented by the presence of daughters and granddaughters, among whom was Miss Arhart, a granddaughter of Lesquereux, who was associated with him in part of his work, and made most of the drawings for his later books. Prof. C. R. Barnes presided over the exercises. Prof. W. A. Kellerman read a tribute to Sullivant from Dr Gray's supplement to the Icones. Mrs. Britton gave a short review of the species named from Sullivant (including twelve North American mosses). Professor Barnes read a tribute to Lesquereux, taken from the Botanical Gazette. Remarks were made and papers read on the Progress in the study of the Hepatica, by Prof. L. M. Underwood; the Moss Flora of Alabama, by Dr. Charles Mohr (read by Professor Earle); the History of the Study of the Mosses, by Mrs. Britton; the Classification of Certain Mosses, by A. J. Grout; the Study of Lichen Distribution in the Mississippi Valley, by Bruce Fink; and Botanical Teaching in the Secondary Schools, by W. C. Stevens and Ida Clendenin. Among the exhibits, those of twelve species of hepaticæ from California, by Prof. F. E. Lloyd; forty-five photographs of American students and collectors made famous by their work in mosses, by Mrs. Britton and Professor Underwood; and six species of mosses discovered and collected originally by Sullivant and Lesquereux near Columbus, deserve special mention.

Rate of Evolutionary Variation in the Past.—Mr. Adam Sedgwick, speaking, in his address at the British Association, of variation, selection, and heredity, having raised the question whether the variability of organisms has ever been different from what it is now, answered it in the affirmative, because it would be absurd to suppose that organisms would remain constant in this respect while they have undergone alteration in all their other properties. According to the Darwinian theory of evolution, one of the most important factors in determining the modification of organisms has been natural selection. It acts by presenting certain favorable variations, and allowing others less favorable to be killed off in the struggle for existence. It will thus come about that certain variations will be gradually eliminated, while the variations of the selected organisms will themselves be submitted to selection, and certain of these will in their turn be eliminated. In this way a group of organisms becomes more and more closely adapted to the surroundings. It would thus appear that the result of continued selection is to diminish the variability of a species. Hence, as selection has been going on all the while, variation must have been much greater in past times than it is now. Following out this train of reasoning, we are