Physiologie. 579 



narrow ränge of experimental error; the relation of air temperature 

 10 time required for colour change is also discussed. The experi- 

 mental part contains numerous data relating to many species, and 

 it was carried out at the Desert Laboratory, Tucson (Arizona), 

 so that many xerophytic plants are included. The topics include: 

 daily march of foliar transpiring power, relation of position upon 

 the plant and age of leaves to their transpiring power, the relation 

 of diurnal to nocturnal foliar transpiring power, transpiring power 

 as an index of xerophytism or of mesophytism, transpiring power 

 of floral plants, relation of foliar transpiring power to the pheno- 

 menon of wilting, transpiring power as an index ofdrought resistance. 

 Amongst the author's general conclusions, the following may 

 be noted. The magnitude of the index ot foliar transpiring power 

 remains approximately constant and low during the night, but sud- 

 denly increases about sunrise, to attain a maximum some time 

 before the daily maxima of temperature and of evaporation. Studies 

 on Verbascum show that the transpiring power of younger and 

 older leaves is not the same, also that the position of a leaf upon 

 the Stern and the variations in structure may intluence transpiring 

 power. Plants growing under more or less arid conditions gave 

 diflferences in the same species. The method offers a simple means 

 for classifying plant forms: mesophytes are plants with a diurnal 

 foliar transpiring power of 0*7 to 1-0. i.e. they give off water vapour 

 from seven-tenths or equal to saturated blotting paper suspended 

 1 m.m. above a surface of water; xerophytes have an index less 

 than 03, while plants with indices between 0-3 and 07 appear to 

 form an intermediate group. It is recognised that such a Classifi- 

 cation has no reference to the water absorbing power of the roots, 

 or the conduction of stems, but it is suggested as something more 

 definite than the vague ecological Classification usually employed. 

 Suggestions are also made as to the application of the method to 

 agricultural problems of drought resistance of species and varieties 

 of crop-plants, and as a means of ascertaining the time when irri- 

 gation should begin. W. G. Smith. 



Büchner, E. und S. Skraup. Ist die Enzymtheorie der 

 Gärung einzuschränken? (Sitzber. phys. med. Ges. Würzburg, 

 p. 27—32. 1914.) 



Die V'erff. treten der Ansicht Rubners entgegen, wonach bei 

 der Gärung zwei verschiedene Vorgänge nebeneinander sich ab- 

 spielen sollen: ein vitaler und ein enzymatischer Zerfall des Zuckers. 

 Ihre Einwände beziehen sich nur auf die gärungschemischen Fragen 

 der Ergebnisse Rubners, die im Einzelnen der Kritik unterworfen 

 werden. Die Verff. kommen zu dem Schluss, dass vorläufig kein 

 Anlass besteht, die Enzymtheorie der Gärung einzuschränken. 



Dörries (Berlin-Zehlendorf). 



Lin^sbauer, K., Zur Kenntnis der Reizleitungsbahnen bei 

 Mimosa pitdica. (Ber. deutsch. Bot. Ges. XXXII. p. 609— 621. 3 Textfig. 

 1914.) 

 Mit Hilfe von Ringelungsversuchen sucht Verf. die Frage der 

 Lokalisation der Reizleitung im Gewebe von Mimosa pudica zu 

 klären. Während Sachs und Pfeffer die Reizleitung in dem Holz- 

 körper des Zentralzylinders suchten, glaubten Haberlandt und 



