Page:Popular Science Monthly Volume 34.djvu/283

Rh own narrow limitations. Moreover, looking at the question from the other side, we find in animals complex organs of sense, richly supplied with nerves, but the function of which we are as yet powerless to explain. There may be fifty other senses as different from ours as sound is from sight." It has been thought that the antennæ in all insects are the organs of hearing, but it has since been shown that the sense of hearing is not confined to one spot, and indeed there is no reason why it should be. Grasshoppers and crickets have ears on their legs, and the crustacean genus Mysis has ears in its tail. Organs of sight, which are the most complex and varied of sense-organs, are treated in this book at greatest length. In regard to the mode of vision by means of compound eyes, the author supports Müller's view that "the picture perceived by the insect will be a mosaic, in which the number of points will correspond with the number of facets." Two interesting chapters are those in which he describes an extension of his earlier experiments on the power of bees and ants to distinguish colors, and answers the objection that the power which he ascribes to ants of perceiving the ultra-violet rays is not true sight, but a sensitiveness of the skin to light. Recognition among ants he believes is effected to a great extent by the antennæ, whether or not smell is the sense which serves for this purpose. Along with some extraordinary manifestations of intelligence in insects, he tells of some interesting cases of apparent stupidity observed by him and by M. Fabre. The closing chapter is on the intelligence of the dog, and is occupied mainly with an account of Sir John's application to his black poodle "Van" of the method used in teaching Laura Bridgman. The poodle apparently learned to bring a card marked "food," "out," "bone," "tea," etc., according to his wants, but when a card of a particular color, or having one, two, or three dark bands on it, was held up to him, and he was sent to fetch a duplicate from among several cards, he generally failed. The author also discusses briefly the question, "Can animals count?" but has reached no definite conclusion on this point. The mental faculties of man and the lower animals are now being investigated as never before. The problems relating to these faculties are being attacked from many different sides, and while much valuable knowledge is resulting from these labors, a great deal of careless observation, unjustified assumption, and baseless theory is being put forth at the same time. Sir John Lubbock, however, is a careful and patient experimenter and a cautious reasoner, and on every page of his writings he shows that his object is the attainment of truth, and not the defense of pet theories.

one who has read any of President Jordan's popular articles on scientific subjects will want a copy of this essay. In it he sets forth, with his well-known vigor and captivating clearness, the main features of the Darwinian theory of the origin of species, and gives samples of the evidence on which this theory rests. He begins by alluding to the variety of the forms of life on the earth, and then calls attention to the unity which exists in this diversity. For instance, "there are dogs and dogs, of all sizes and styles, yet enough alike for us to regard them as belonging to one original species." Then there are other dog-like animals—wolves, coyotes, jackals, foxes—which we must regard as first-cousins to the dogs. Each of these races has still other relatives, further removed from the dog-type, and, proceeding thus, we have at last all animals of the mammalian class "joined together by a branching chain of apparent relationship—a chain of homologies." The problem before us is, "What is the origin of variety in life, and how does it come that this variety is based on essential unity?" The author then reviews the answers which have been given to this problem by Linnæus, Cuvier, Lamarck, Saint-Hilaire, Goethe, and Agassiz. Darwin's answer to the problem follows, and is stated partly in quotations from his works and his letters, and is supplemented by illustrative cases by the author. How Darwinism explains the facts of geological distribution, and of degeneration both of type and of individual parts in the organism, is next explained, and a brief account of the evidence which embryology brings to the support of the theory of evolution, contributed by Dr. J. S. Kingsley, is here inserted.