The reader will find here the soundest, healthiest acceptance of the Darwinian theory of natural selection. He penetrates the mists and fogs of philosophical vagaries and follows the dictum of Tyndall, who, in presenting the essentials of a discussion, says, "Not with the vagueness belonging to the emotions, but with the definiteness belonging to the understanding" we are to study these matters. It is fact, fact, fact. The honest "I do not know" inspires the reader with a confidence that obscure points are not to be juggled with. He insists that the principles of science are physical, that a mechanical interpretation of Nature is reasonable and just. Referring to Huxley, he remarks that faith and hope are good things, no doubt, and (quoting from Huxley) "expectation is permissible when belief is not," but experience teaches that expectation or faith of a master is very apt to become belief in the mind of the student," and (again from Huxley) "Science warns us that the assertion which outstrips evidence is not only a blunder but a crime." In the chapter of Nature and Nurture he brings many potent facts and arguments against the idea of the transmission of acquired traits. Without copious extracts it is impossible to do justice to this masterly presentation of the subject. The chapter abounds in aphorisms, as indeed do other portions of the work; and these alone, if serially collated with their contexts, would make a valuable little handbook for the student of biology. His chapter on Lamarck is equally strong, and the fallacies of Lamarckianisms have never been so clearly shown. "The contrast between what we may call the solicitude of Nature to secure the production of new beings, and the ruthlessness with which they are sacrificed after they have come into existence, is a stumbling-block to the Lamarckian, and the crowning glory of natural selection in that it solves this great enigma of Nature by showing that it is itself an adaptation and a means to an end, for the sacrifice of individuals is the means for perfecting the adjustments of living things to the world around them and for thus increasing the sum of life." "Whole books have been written on the marvelous fitness of the structure, the instincts, and the habits of the worker of the honeybee for its life of active industry--a life in which the male has no share, and from which the female is cut off by her seclusion in the depths of the hive, and by her devotion to her own peculiar duties. While the queen and the drones are well fitted for their own parts in the social organization of the hive, these duties are quite simple, and very different from the duties of the workers; and as these latter do not normally have descendants, and as they never under any circumstances have female descendants, all the workers are the descendants of queens and not of workers.