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546 NEW BOOKS. Two new Appendices contain a summary of the evidence for the In- heritance of Functionally Wrought Modifications, and an essay upon Spontaneous Generation and the Hypothesis of Physiological Units. The most interesting of these additions, to the philosophical reader, will probably be the arguments alleged in favour of ' direct equilibration ' and the discussion of the nature of life. Fuller notice is reserved until the publication of the second volume. The Dawn of Reason : Mental Traits in the Lower Animals. By ,T. WEIE. New York : The Macmillan Co., 1899. Pp. xiii., 234. Price $1.25. Comparative psychologists fall into two classes : the credulous and the sceptical. Dr. Weir, who belongs to the former category, and holds that " intelligent ratiocination performs an important role in the drama " of animal life, has brought together in this little volume a mass of data, gained at first and second hand, which had for the most part already seen the light in the form of magazine articles. This fact may account for the unnecessary repetitions of anecdote that disfigure his pages. He believes in the development of mind from reflex action, and in the exist- ence of an unconscious as well as a conscious mind. The book before us is principally concerned with the conscious mind of insects. Dr. Weir is a good observer, but a poor interpreter. Our old friend, the aesthetic spider, revives under his hands. Adaptation of colour to environment (' tinctumutation ') and the homing instinct are referred to ' auxiliary senses '. It is well that, as the Preface states, the author " does not claim infallibility " : for psychos is not the Greek for mind. Defective Eyesight : the Principles of its Relief by Glasses. By D. B. ST. J. ROOSA. London and New York : Macmillan & Co., 1899. Pp. 193. Price 4s. 6d. ; $1. This little book is a recasting of the author's The Determination of the Necessity for Wearing Glasses, published in 1888. It is a useful and interesting essay, written by a competent man. The volume shows some signs of hasty preparation, both in arrangement and topography : the dioptric system is presupposed until page 172, there are minor repeti- tions in the early chapters, Salvinus Armatus figures also as Sal vino degli Armati, etc. ; but these and similar slips can easily be corrected in a second edition. The work deals with the measurement of visual acuity (test types are given in an appendix) ; defects of accommodation (presbyopia) ; errors of refraction (myopia, hypermetropia, regular corneal astigmatism) ; general asthenopia ; and the use of spectacles and eye-glasses. A History of Physics in its Elementary Branches : including the Evolution of Physical Laboratories. By F. CAJORI. London and New York : Macmillan & Co., 1899. Pp. viii., 322. Price 6s. 6d. ; $1.60. This is a simply written and selective history of physical science, " in- tended mainly for the use of students and teachers of physics," by the author of the Elementary History of Mathematics, which we noticed some time since. While it will doubtless serve the purpose towards which it is primarily directed, it may also be cordially recommended to the general reader, including the student of philosophy and psychology. The treatment is by periods : the Greeks, Romans, Arabs, Europe during