No. 2, June, 1921] PHYSIOLOGY 209 



1447. Wester, D. H. Ueber den merkwiirdigen Verlauf der Ureasewirkung eines Soya- 

 bohnenextraktes beim ErwSrmen auf 37°. [The peculiar action of the urease in soybean 

 extract when heated at 37°C.] Pharm. Zentralhalle 61:293-295. 1920.— The author found 

 that the action of urease on soybean extract changes considerably when kept at 37°; thus he 

 found that while the urea number (i.e., the number of mg. of urea converted by the urease 

 solution) was 126 on the first day, after 7 days' standing it had been reduced to 47 and after 

 14 days to 38.2, and had increased after 21 days to 90, declining after 26 days to 85, and after 

 35 days to 60.3.— H. Engelhardt. 



PHYSIOLOGY 



B. M. DuGGAR, Editor 

 Carroll W. Dodge, Assistant Editor 



(See also in this issue Entries 769, 770, 778, 779, 785, 791, 805, 812, 942, 944, 948, 1069, 1116, 

 1118, 1147, 1163, 1211, 1229, 1357, 1369, 1374, 1375, 1376, 1429, 1430, 1431, 1445, 1447, 1509, 

 1514, 1518, 1526, 1529, 1533, 1535, 1574.) 



GENERAL 



1448. Clark, W. M. The determination of hydrogen ions. 317 p., S8 fig. Williams & 

 Wilkins Co.: Baltimore, 1920. — In his preface the author points out interesting biological 

 and chemical investigations as landmarks in the comprehension and measurement of "acid- 

 ity," and while recognizing that the hydrogen ion may be a center of great interest because 

 it is a dissociation product of so many compounds with which the biochemist deals, he also 

 indicates that it is a factor which should not be permitted to "obscure possibilities of broader 

 generalizations." — The book is written in response to the need of a detailed exposition of the 

 two methods — colorimetric and electrometric — in daily use to determine hydrogen-ion con- 

 centration. Accordingly, Chapter I is concerned with some of the general relations among 

 acids and bases, including a discussion of the Ph scale and buffer action. This is followed by 

 captions (pp. 38-96) in which are presented discussions of the colorimetric procedure, theory 

 of indicators, choice of indicators, buffer solutions, protein and salt errors, and the value and 

 limitations of approximate determinations with indicators. Chapters VIII-XVII deal 

 with the electrometric method, including the theoretical aspects as well as detailed descrip- 

 tions of the hydrogen and calomel electrodes and electrode vessels, and the potentiometer 

 and equipment, also errors of measurement, and standardization methods. A brief chapter 

 relating to supplementary methods is followed by a more elaborate presentation of "appli- 

 cations" intended primarily for the biochemist and biologist, but considered by the author 

 as merely a "cursory review" and as an index to the bibliography. The bibliography extends 

 over 64 pages and includes some titles as late as 1919 and 1920. There are 9 pages of tables. — 

 B. M. Duggar. 



1449. Thatcher, R. W. The chemistry of plant life, xvi + 268 -p. McGraw-Hill Book 

 Co.: New York, 1921. — This book is intended to serve primarily as a handbook dealing with 

 the constitution of the compounds involved in plant growth, likewise the conditions under 

 which such compounds undergo chemical changes in the protoplasm. After a brief chapter 

 on "plant nutrients," encompassing the mineral nutrients and their roles, the author sets forth 

 in a few pages (chapter 2) on the organic components of plants the significance of the materials 

 to be treated, and classifies the important groups of compounds as follows: The carbohydrates 

 and their derivatives, the glucosides and tannins; the fats and waxes; the essential oils and 

 resins; organic acids and their salts; the proteins; the vegetable bases and alkaloids; and the 

 pigments. Ten of the remaining 16 chapters (150 pages) are devoted to the description and 

 discussion of these groups of substances. These sections are preceded by a chapter on 

 photosynthesis, in which there is elaborated the trend of investigations following Baeyer's 

 suggestion, now frequently known as Baeyer's formaldehyde hypothesis. The remaining 5 

 chapters deal with enzymes, the colloidal condition, the physical chemistry of protoplasm, 

 accessory stimulating agencies, and adaptations. — B. M. Duggar. 



BOTANICAL ABSTRACTS, VOL. VIII, NO. 2 



