Turgor and of Temperature on Growth . 387 
Vicia Faba to both sudden and to gradual changes of tem- 
perature between io° and 20° R., and found the growth-rate 
to depend solely on the absolute temperature, the act of 
change being entirely without influence. 
Askenasy 1 , with a more accurate method of measurement, 
found that the influence due to a sudden change of tempera- 
ture depended on the position of the lower limit. When the 
minimum temperature used still permitted growth, the change 
to the higher degree was followed by an immediate assumption 
of the rate of growth characteristic for the new temperature. 
When, however, the minimum temperature was near the zero 
point, the transfer to the higher temperature was followed by 
a more or less tardy assumption of the normal growth-rate. 
Pfefler 2 noted a similar gradual return of growth after roots 
which had been in a temperature of 0-5° C. for 12 hours were 
brought into a warmer medium. 
Godlewski 3 saw very similar results in the case of epicotyls 
of Phaseolus vulgaris , when they were exposed to sudden 
changes of the temperature of the surrounding air. Whether 
the temperature was raised or lowered, a temporary decrease 
of growth-rate followed. 
Pfefler 4 found that changes of temperature caused the 
opening and closing of flowers of Crocus and of Tidipa by 
bringing about unequal growth in antagonistic parts of the 
perianth-members. A rising temperature caused a more rapid 
growth of the upper part, and opening followed ; a falling 
temperature, on the other hand, caused a more rapid growth 
of the under part, and thus the closing of the flower. The 
same author 5 observed that changes of temperature act as 
1 Askenasy, Ueber einige Beziehungen zwischen Wachsthum und Temperatur. 
Ber. d. deutsch. bot. Gesellsch., Bd. VIII (1890), p. 75. 
2 Pfefler, Druck und Arbeitsleistung durch wachsende Pflanzen. Abh. d. 
Konigl.' Sachs. Gesellsch. f. Wissensch., Bd. XX, Heft III, pp. 893, 354. 
3 Godlewski, Ueber die Beeinflussung des Wachsthums der Pflanzen durch 
aussere Faktoren. Anz. d. Akad. d. Wissensch. in Krakau, 1890, p. 166. 
4 Pfefler, Physiologische Untersuchungen. Leipzig, 1873, p. 194. 
5 Pfefler, Die periodischen Bewegungen der Blattorgane. Leipzig, 1875, 
P- ! 35 . 
