614 W. Wendler: Physikalische Physiologie 1923 —1924 [40 
Pflanzen. (Flora N.F.16, 1923, p. 296-311, 1 Textabb.) — Ref. in Bot. 
Ctrbl., N.F. 3, 1924, p. 297—298. 
429. Karling, J. Ss. A preliminary account of the influence of 
lisht and temperature on growth and reproduction in Chara 
fragilis. (Bull. Torrey Bot. Club 51, 1924, p. 469—488, 3 Taf.) — Ref. in Bot. 
Ctrbl., N. F. 6, 1925, p. 36—37. | 
430. Kaufmann, Ss. Beitrag zur Kenntnis des Etiolements. 
Diss. Naturwiss. Fak. Univ. Frankfurt a. M. 2, 1922/23, p. 158—161. — Ref. 
in Bot. Ctrbl., N. F.7, 1926, .p. 267—268. 
431. Keener, Alice EE A study of the factors concerned in the 
reddening of leaves of Diervilla Lonicera. (Amer. Journ. Bot. 11, 1924, 
p. 61—77, mit 3 Textfig. u. 1 Taf.) — ‚‚l. Mature leaves of Diervilla lonicera 
Mill. in the Douglas Lake region redden in sunshine areas, but remain green 
in shaded locations. 2. Red plants of D. lonicera, if artificially shaded by screens 
cutting off at least one half of the vertical rays of the sun, became almest 
entirely green. 3. Transpiration in red plants, as observed by the potometer, 
was greater than in green plants in seven of the nine cases noted. 4. Stomates 
of red leaves were closed, those of green leaves were open, as observed by the 
xylol method. 5. Reduction of evaporation in artificial shade, as shown by 
standardized Livingston atmometers, approximated that in natural shade. 
6. Soil in which red plants were growing contained a lower percentage of moi- 
sture than soil in which green plants were growing (average, red plants 1,47 
percent; green plants 1,75 percent). 7. Red leaves in six cases out of nine 
contained a higher percentage of water than green leaves (average. red 
leaves 69,4 percent, green leaves 67,2 percent, og moist weight). 8. Red 
plants in sand, artifieially watered, tend to redden even in the shade. Red 
plants in good soil, artificially watered and exposed to sunligsht, show 
slight reddening. 9. Watering plants by artificial means in a measure controls 
reddening of leaves. 10. Red plants in poor soil, transplanted to a more ex- 
posed location, remained green. 11. The hydrogen-ion concentration of soil 
at the root level of both red and green plants ranges from pp 5,6. to pp 6,2. 
12. The factors concerned in reddening are: a) Vertical rays of the sun. b) Kind 
of soil — whether sand soil poor in humus, or soil rich in humus. c) Water 
eontent of soll. d) Amount of evaporation and transpiration.“ 
432. Koningsberger, V. J. Lichtintensität und Lichtempfindlich- 
keit. (Recueil des travaux botaniques neerlandais 20, 1923, p. 257—321.) — 
Aus verschiedenen Versuchen konnte Verf. feststellen, daß die Empfindlich- 
keit für höhere Lichtintensitäten nicht durch kürzere oder längere Vorbelich- 
tungen mit niedrigeren Intensitäten abgeändert wurde; jede Intensitäts- 
erhöhung ruft eine neue Reaktion hervor. A. Timmermans (Leiden) 
433. Lamberg, 6. und Mitscherlich, E.A.- Über das Licht als 
Wachstumsfaktor. (Zeitschr. f. Pflanzenern. usw. 1, 1922, p. 291—298.) 
434. Lapieque, L. et Kergomard, T. Acidification par l’asphyxie 
chez les Spirogyres; reactions morphologiques consecutives. 
(C. R. Soc. Biol. 88, 1923, p. 1081-1083.) — Ref. in Bot. Ctrbl., N. F. 3, 1924, 
p-. 71—72. — Bei Dunkelheit wird das Quellwasser sauer, bei Licht alkalisch. 
435. Leonov, N. D. et Sossiedow, N. J. Observations upon daily 
movement of stomata. (Bull. Univ. Asie Oentr. Taschkent 8, 1924, p. 71 
bis 78, 4 Diagr. Russisch m. engl. Zusfassg.) — Ref. im Bot. Ctrbl., N. F.7, 
1, Tüo Te 
