268 W. Wendler: Chemische Physiologie 1917— 1919 [12 



water to become unfree, as indicated by its refusal to freeze, (2) in measuring 

 quantitatively the amount of water thus becoming unfree, (3) in determining. 

 linder certain empirical eonditions, the wilting eoefficient of soils, and (4) in 

 classifying, under certain empirical eonditions, the water in the soil into free, 

 eapillary, physically adsorbed, and chemically combined." 



102. Brooks, S. C. A n e w method o f studying permeability. 

 (Bot. Gaz. 64, 1917, p. 306—317.) — Summary: „1. The protoplasm of Lami- 

 naria is normally permeable to the salts of sea water. 2. Sodium salts cause 

 an increase of permeability which eulminates in deatli. 3. Calcium and lantha- 

 num salts cause a decrease in permeability, followed by an increase which 

 eulminates in death." Vgl. ausführliche Besprechung durch Ruhl a n d in 

 Ztschr. f. Bot. 13. 1921, p. 323—325. 



103. Brooks, S. C. Methods o f studying permeability o f 

 protoplasm to salts. (Bot, Gaz. 64, 1917, p. 230—219.) — Summary: 

 „From a consideration of the methods heretofore used in the study of perme- 

 ability it would appear that the Steps most essential to further progress to- 

 ward the Solution of the problem are: 1. a thorough analysis of the various 

 disturbing factors in the methods involving chemical determinations and the 

 satisfactory interpretation of the results secured by such methods; 2. the same 

 type of analysis of the methods depending on turgor, with special reference to 

 the possible effect of exosmosis; and 3. the establishment of methods of deter- 

 mining progressive changes in permeability without the various disadvantages 

 of the other methods. — The writer hopes to show in subsequent papers that 

 the diffusion method. which he has devised, answers these requirements, and 

 that it is also possible to interpret satisfactorily the data obtained by certain 

 methods dependent upon the use of turgor as a criterion." 



104. Dernby. K. Gr. E n meto d a 1 1 standardisera n ä r 1 ö s - 

 ningar v i d odlingen avpneumokokker. [Eine Methode zur Stan- 

 dardisierung der Nährlösungen bei der Kultur von Pneumokokken.] (Meddel. 

 frän K. Vetenskapsakad. Nobelinst, V, 1919, Nr. 26, 8 pp.) — Die Pneumokokken 

 gedeihen nur innerhalb eines sehr eng begrenzten H-Ionenkonzentrations- 

 gebietes. Wachstum findet nur zwischen pH 7 und 8 statt, Daraus ergibt sich 

 die Notwendigkeit, Nährlösungen einer ganz bestimmten H-Ionenkonzentra- 

 tion anzuwenden. "Wegen der Säureproduktion der Pneumokokken empfiehlt 

 es sich, das anfängliche pH der Nährlösung auf 7,7—8,2 einzustellen. Als Hilfs- 

 mittel hierzu empfiehlt Verf. die Clarkschen Indikatoren und eine Modifikation 

 des "Walpoleschen Komparators. . Es ist zweckmäßig, der Nährlösung 8,35 g 

 Na 2 HP0 4 , 2 H 2 und 0,47 g KH2PO4 pro Liter als Puffer hinzuzufügen. 



(Holländer. 



105. Duggar, B. M. The micro-colorimeter in the i n d i c a - 

 tor method of hydrogen ion determination. (Ann. Missouri 

 Bot, Gard. 6, 1919, p. 179—181.) 



106. Duggar, B. M. and Dodge, C. W. The u s e f the eolorimeter 

 in the i n d i c a t r method of H - i n determination with b i - 

 1 o.g i c a 1 fluid s. (Ann. Missouri Bot. Gard. 6, 1919, p. 61—70, mit 1 Fig.) 

 — The authors conclude from this work on the use of the eolorimeter that 

 l st the difficulties involved in the approximate determination of the hydrogen 

 ion concentration of Solutions exhibiting color may be largely overcome; and 

 2 nd the useful ränge of certain brilliant indicatorsmay be so considerably ex- 

 tended that the number of indicators employed may be materially reduced. 



