116 ' PHYSIOLOGY [BoT. Absts., Vol. X. 



739. Casale, Luigi. Un metodo per la determinazione dell' energia acida nei vini. [An 

 electrochemical method for the determination of true acidity in wines.] Staz. Sper. Agrarie 

 Ital. 53: 29S-308. 1920. — The method is based upon the fact that the affinity of acids for 

 bases is a measure of their "strength," and that a base in presence of 2 acids will combine 

 with them in a ratio proportional to their strength, so that an equilibrium will be reached when 

 each acid is isohydric with its respective salt and also with the other acid present in the sys- 

 tem. [See also Bot. Absts. 10, Entry 737.] — A. Bonazzi. 



740. Cauda, A., e C. Mexsio. Concentrazione molecolare del succhi di vita. [Molecular 

 concentration of the sap of Vitis.] Staz. Sper. Agrarie Ital. 53 : 317-331. 1920. — The Ostwald- 

 Luther method was applied in the determination of the conductivity of sap collected from the 

 vines in the field or from the crushed young twigs of several varieties of Vitis. It was found 

 that the index of conductivity varies throughout the season and that it increases up to a maxi- 

 mum and then decreases. Conductivity measurements are influenced by the presence, in the 

 sap, of organic substances and especially those of an acid character. As a general rule the 

 conductivity of a sap increases with the increase of mineral substances in solution, and for 

 a constant quantity of mineral substances conductivity increases with the increase of ex- 

 tractive materials. Differences in the conductivity of sap from different branches of the 

 same tree may sometimes be quite large, and again striking differences may be obtained in 

 saps obtained from trees of the same variety but of different ages, from trees under different 

 systems of culture, and from different graftings. The authors state that it is quite probable 

 that conductivity of the sap may be proportional to the production of fruit. — A. Bonazzi. 



741. D., C. [Rev. of: Ostwald, Wo. Grundriss der KoUoidchemie. Erste Halfte. 

 (Outline of colloid chemistry.) 5th ed. Th. Steinkopff: Dresden and Leipzig, 1919. ISmarks.] 

 Zeitschr. Phys. Chem. 96: 379. 1920. 



742. D., C. [Rev. of : Ostwald, Wo., und Paul Wolski. Kleines Praktikum der KoUoid- 

 chemie. (Small manual of colloid chemistry.) 169 p. Th. Steinkopff: Dresden and Leipzig, 

 1920. Kart. 15 marks.] Zeitschr. Phys. Chem. 96: 379. 1920. 



743. Frazer, Chas. G. The action of methylene blue and certain other dyes on living and 

 dead yeast. Jour. Phys. Chem. 24: 741-748. 1920. — In an attempt to find a "criterion of 

 death" the "behavior of nine dyes with living yeast and yeast killed by boiling or by the action 

 of phenol" was studied. Of these dyes gentian violet, neutral red, and safranin are too toxic; 

 Congo red has too little effect on dead cells; fuchsin, neutral red, and safranin are too faint; 

 while erythrosin, eosin, methyl green, and Kahlbaum's methylene blue 6B extra (Griibler's 

 methj^lene blue and Merck's methylene blue being more toxic) could be used. Erythrosin 

 is better than eosin while methjd green hinders reproduction in some media without staining. — 

 On the whole, erythrosin and methylene blue seem to be the best. Data secured bj' using 

 methylene blue with various reagents likely to be used in quantitative toxicological work with 

 yeast are given. — H. E. Pulling. 



744. Freundlich, H. [Rev. of: Poschl, Viktor. Einfiihrung in die KoUoidchemie. 

 (Introduction to colloid chemistry.) 5th revised and enlarged ed., 148 p. Theodor Steinkopff: 

 Dresden and Leipzig, 1919. 7 marks.] Zeitschr. Phys. Chem. 94: 506. 1920.— The book 

 is regarded as containing too many errors and too much material of only historical interest 

 to be the good introductory text it was designed to be and which is needed. — H. E. Pulling. 



745. Harris, J. Arthur, Ross Aiken Gortner, and John V. Lawrence. The osmotic 

 concentration and electrical conductivity of the tissue fluids of ligneous and herbaceous plants. 

 Jour. Phys. Chem. 25: 122-146. 1921. — "Studies in the Arizona deserts, in the Jamaican 

 montane rain forest, and in the mesophytic habitats of the north shore of Long Island have 

 shown that the osmotic concentration, as measured by the cryoscopic method, is far higher 

 in the leaf tissue fluids of ligneous than of herbaceous species. Because of the wide range, 

 geographic and ecological, over which the data leading to this conclusion were obtained the 



