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THE POPULAR SCIENCE MONTHLY.

use in differentiating a man from his fellows; and the finger prints are found to afford one of the most certain marks of identification. The question whether patterns are transmissible by descent is answered affirmatively; and this leads to the estimation of their use in indicating race and temperament. In the last chapter the right is discussed of the nine fundamentally differing patterns to be considered as different genera, and of their more characteristic varieties to rank as different genera or species, as the case may be, with affirmative conclusions.

Sound and Music. By the Rev. J. A. Zahm. Chicago: A. C. McClurg & Co. Pp. 452. Price, $3.50.

The author of this work is Professor of Physics in the University of Notre Dame. The main purpose of the book is to give musicians and general readers an exact knowledge, based on experiment, of the principles of acoustics, and to present at the same time a brief exposition of the physical basis of musical harmony. The author believes that, in view of the attention now given to theoretical as well as practical music in European and American conservatories, this presentment can not be considered altogether untimely. The treatise is based on the recent and most exact observations of modern physicists, most prominent among whom are Helmholtz and Koenig, as well as the works of the older acousticians, and is intended to include a summary of all that has been learned and determined down to the date of publication. To Koenig, the latest of these investigators, and the one probably who has carried our knowledge of the philosophy of music to the most successful results yet obtained, personal obligations are acknowledged. The volume has grown out of a course of lectures that were given in 1891 in the Catholic University of America, Washington, D. C. These, however, have been thoroughly revised, with the purpose of making the exposition of the subject more complete than was possible in lectures actually delivered, so that it is practically a new work. Yet the lecture form has been retained as being more animated and picturesque, and more in keeping with the character of a work that deals so largely with apparatus and experiments. Of the illustrations and experiments many were prepared expressly for this work, while others are to be found only in the more recent French and German treatises on sound and music. The first chapter, beginning with a reference to the relation of the science to the art of music, is devoted to the explanation of the Production and Transmission of Sound and the Nature of Sonorous Vibrations. In the next two chapters the laws of Loudness or Intensity of Sound and Pitch are considered, with a description of Koenig's Grand Tonom├ętre Universel, and the subjects of Telocity, Reflection, and Refraction of Sound. The topics of Musical Strings, Vibrations of Rods, Plates, and Bells, and Sonorous Tubes follow; after which come the theoretical subjects of Resonance and Interference, Beats and Beattones, the Quality of Sound, and Musical Intervals and Temperament.

Text-book of the Embryology of Man and Mammals. By Dr. Oscar Hertwig, Professor Extraordinarius of Anatomy and Comparative Anatomy, Director of the II Anatomical Institute of the University of Berlin. Translated from the third German edition by Edward L. Mark, Ph. D., Hersey Professor of Anatomy in Harvard University. With 339 Figures in the Text and Two Lithographic Plates. London: Swan, Sonnesehein & Co. New York: Macmillan & Co., 1892. Price, $5.25.

The fact that this work possessed sufficient merit to go through three editions in German in the four years following its first publication, implies an intrinsic merit; for there is no paucity in the literature of this subject, while the new discoveries that are constantly being reported by investigators tend to make a comparatively recent book behind the times, speaking from a scientific standpoint.

In the first chapter the sexual products are described, and following this is an explanation of the phenomena of the maturation of the egg and of the process of fertilization, the author presenting the theory that the female nuclear substance transmits the peculiarities of the mother, the male nuclear substance those of the father. This is an expansion of the theory of fertilization into one of transmission.

We do not think that the translator has been felicitous in his choice in using the term "process of cleavage" for the more