314 s. KUSANO : TRANSPIRATION OF 



have been confined to the vegetating season. That evergreen 

 trees are constantly supplied with water even in winter, was 

 first observed by Hales/' and then by DuhameF. Trevi- 

 ranus"\ in his "Physiologie der Gewächse," says "In An- 

 sehung der Jahreszeiten ist sie (Transpiration) unter gleichen 

 Umständen im Frühjahre und Sommer am stärksten : im Herbste 

 nimmt sie sehr ab und im Winter bemerkt man keine mehr." 

 In the year 1860, T. Hartig^' made some experiments on trans- 

 piration with Picea, a meter high, in milder winter, and found 

 that the plant gave off from about 100 to 125 grams of water 

 a day (V10-V4 Pfwnd) ; but as he gave neither the area nor weight 

 of the transpiring part, we are unable to calculate the actual 

 intensity of transpiration. Afterward Burgerstein^'^ pointed out 

 in 1875, the relation of transpiration to lower temperatures and 

 ascertained that transpiration of cut-branches of TaxiLS haccata 

 was found to occur even in temperatures below zero. According 

 to the results obtained by the latter botanist, Taxus haccata 

 transpired in an hour at -2°C., 0.288 per cent, and even at 

 -10.7°C., 0.019 per cent, of its fresh weight. A similar experiment 

 was made by Wiesner and Paclier^'* with leafless cut-branches 

 of Aesculus. In branches either one or three years old, the 

 loss of w^ater at a temperature of-13°C. could still be observed. 

 The above instances sufficiently prove that although the 



1) Hales, Statik der Gewächse 1748, p. 29. 



2)Duliamel, De l'exploitation des bois 17G4, Bd. I, p. 337. 



3) Treviranus, Physiologie der Gcwiiclise 1835, I5d. I, p. 488. 



4) T. Hartig, Ueberdie Bewegung des Saftes in den Ilolzpflanzen. Bot. Ztg., Bd. XIX, 

 1861, p. 17; and Lehrbuch für Förster 1877, 11 Aufl., Bd. I, p. 252. 



5) Burger st ein, Ueber die Transpiration von Taxupzwcigcn bei niederen Temperaturen. 

 Oesterr. Bot. Zeitschr., Bd. XXV, 1875. 



6) Wiesner und Fächer, Ueber die Transpiration entlaubter Zweige und des Stammes 

 der Rosskastanie. Oesterr. Bot. Zeitschr., lîd. XX\', 1875. 



