EFFECT OF TEMPERATURE ON THE CARBOHYDRATE-CONTENT. 63 



From these results it becomes evident that at higher temperatures the 

 plant tends to the formation of polysaccharides, while at lower temperatures 

 a condition of general inversion seems to prevail. 



TABLE 29. 



A similar modification of the carbohydrates concomitant with changes in 

 temperature has been observed in a variety of other plants. Lidforss* 

 showed that all evergreen leaves in temperate latitudes are quite starch-free 

 from the beginning of December and throughout the winter. With the 

 advent of higher temperatures in spring starch again appears in the chloro- 

 plasts. Similar observations have been made by Mer/ Haberlandt,* and 

 Schultz.* That temperature is here actually the determining factor is 

 demonstrated by the fact that when the leaves during any time in the winter 

 are brought to a higher temperature, starch formation takes place very 

 readily. Maximow 5 has made similar observations and has called atten- 

 tion to the high content of glucose in evergreen leaves during the winter. 

 The low eutectic point of glucose solutions is regarded as a protection 

 against freezing. Miyake ' reports similar conditions existing in Japan. 

 In the winter many evergreen leaves in the middle and southern parts of 

 Japan contain more or less starch, while in the colder parts the leaves are 

 found to be starch-free. The very interesting experiments of Czapek T bear 

 directly upon the question under discussion. He showed that at low tem- 

 peratures the sugar concentration in the cell must be very much higher in 

 order that starch formation may take place than at higher temperatures. 



1 LIDFOBSS, B. Zur Physiologie und Biologic der wintergruenen Flora. Bot. Central- 



blatt, 68, 33-44, 1896. 

 1 MER, F. De la constitution et des fonctions des feuilles hivernales. Bull. Soc. Bot. 



France, 23, 231, 1876. 



* HABEBLANDT, G. Vergleichende Anatomie des assimilatorischen gewebesytems der 



Pflanzen. Jahrb. f. wiss. Bot., 13, 74, 1882. 



* SCHULTZ, E. Ueber die Reservestoffe in immergruenen Blaettern. Flora, 71, 223, 



1888. 

 5 MAXIMOW, N. A. Chemische Schutzmittel der Pflanzen gegen Erf rieren. Ber. d. 



deut. bot. Ges., 30, 52-65, 293-305, 504-516, 1912. 

 ' MIYAKE, K. On the starch of evergreen leaves and its relation to photosynthesis 



during the winter. Bot. Gaz., 33, 321-340, 1902. 

 7 CZAPEK, F. Der Kohlenhydrat-Stoffwechsell der Laubblaetter im Winter. Ber. d. 



deut. bot. Ges., 19, 120-127, 1911. 



