Geology and Natural History. 123 



18. An Introduction to the Chemistry of Plant Products / by 

 Paul Haas and T. G. Hill. Pp. xii, 401. London and New 

 York, 1913 (Longmans, Green and Co.). — In view of the unmis- 

 takable success with which those aspects of biochemistry dealing 

 more particularly with animal physiology have been investigated 

 and presented in text-book resume in recent years, it is surpris- 

 ing that so few efforts have been made along similar lines in the 

 domain of the chemistry of vegetable forms. The present work 

 aims to furnish an introductory account of the chemistry and bio- 

 logical significance of some of the most important substances 

 occurring in plants. Wherein the distribution of emphasis differs 

 from what one finds in a manual of animal physiological chem- 

 istry is indicated by the major subdivisions of the text into : 

 1. fats, waxes, oils, and phosphatides ; 2. carbohydrates ; 3. glu- 

 cosides; 4. tannins; 5. pigments; 6. nitrogen bases; 7. colloids; 

 8. proteins ; 9. enzymes. A few of the important quantitative 

 methods like those applied to the characterization of fats and the 

 estimation of sugars and proteins are described in detail. 



The authors have exhibited ingenuity in applying the newer 

 knowledge in this field to the specific needs of students of botany. 

 The result represents an innovation in the way of indicating the 

 progress which the special chemistry of plants has lately made. 



L. B. M. 



19. Modern Problems of Biology ; by Charles Sedgwick 

 Mltstot. Pp. ix, 124, with 53 illustrations. Philadelphia, 1913 

 (P. Blakiston's Son & Co.). — The six lectures, delivered by the 

 American exchange professor at the University of Jena in 1912, 

 and originally published in German, are here rendered in English. 

 These lectures touch upon the most fundamental problems of 

 modern biology, the topics discussed being : the new cell doc- 

 trine; cytomorphosis; the doctrine of immortality, the develop- 

 ment of death; the determination of sex; and the notion of life. 

 Having been designed for a popular audience, the presentation is 

 made in as simple language as the subject will permit. This little 

 book furnishes a reliable summary of the present state of our 

 knowledge on these important topics. There is appended an ex- 

 planatory list of the principal publications to which reference is 

 made. w. R. c. 



20. A Laboratory Manual of Invertebrate Zoology ; by Gilmatst 

 A. Drew. Second edition, revised. Pp. ix, 213. Philadelphia 

 and London, 1913 ( W. B. Saunders Co.). — The original edition 

 of this book has been widely adopted. The revised edition incor- 

 porates a number of changes resulting from more recent labora- 

 tory experience, with directions for the study of a few additional 

 forms. The inclusion of a brief literature list for each topic will 

 prove of value both to teacher and student. w. r. c. 



21. Heredity and Memory ; by James Ward. Pp.56. Cam- 

 bridge, 1913 (University Press). — This lecture, delivered atNewn- 

 ham College in 1912, explains and supports the psychologic or 

 mnemic theory of heredity, which has received considerable 



