626 EXPERIMENT STATION KECOED. 



Investigations on the assimilation of carbohydrates by Beta vulgaris, 

 W. RuHLAND (Jahrb. Wiss. Bot. [Pringsheim], 50 {1911), No. 2, pp. 200-251).— 

 The author studied the movements and storing of the principal carbohydrates 

 in a variety of sugai* beet, confining attention chiefly to cane and invert sugar. 

 The results of this work may be summarized as follows: 



Sugar moves in these plants not principally as cane sugar, according to the 

 generally accepted view of Czapels, but as invert sugar, perhaps especially as 

 fruit sugar, toward the roots, there to be condensed to cane sugar. Both 

 invert and cane sugar are found moving from the leaves toward the roots, but 

 the only conversion that tal^es place in the roots is of invert to cane sugar. In 

 the second period of vegetation the cane sugar only is found to move in the 

 roots, and this is broken up only on entrance into the leaves. In the axes of 

 the flower-bearing twigs the cane sugar probably travels upward to be inverted 

 in the young flowers. The cells of the leaves and petioles are permeable for 

 rafBnose, cane sugar, maltose, and more or less, for all the hexoses tested, out 

 of which they are able to construct starch. The degree of permeability as 

 determined by the plasmolytic method is exceedingly small for cane and invert 

 sugar, and much greater for glucose and fructose. On the other hand, regu- 

 latory changes in permeability may be discoverable. The cells of the roots 

 show still less permeability for raflinose, cane sugar, and maltose than do the 

 cells of the foliage. 



The exosmosis of the fully grown roots was carefully studied. Cane sugar is 

 given out chiefly in opposition to the well-known earlier conclusions of Purie- 

 witsch. The sieve tubes are not more permeable for sugar than the other cells, 

 and can hardly play any particular part in sugar movement. Invertase in the 

 sugar beet is soluble in water and occurs persistently in all parts of the plant 

 except the seeds and full-grown roots. The roots of the very young seedlings 

 also contain invert sugar. Growing roots rapidly lose their capacity for inver- 

 tase, which is confined to the younger portions not only in the first period of 

 growth, but in the second also. A regulatory manufacture of invertase takes 

 place following the stimulus of an injury. The intramolecular respiration 

 observed by Stoklasa as a result of which cane sugar is converted appears to 

 show that this activity takes place only on traumatic stimulation. Invert 

 sugar is not localized in particular cells separated from cane sugar. Consid- 

 ering the behavior of the cell contents it does not appear that cane sugar is 

 inverted by an enzym in the cell sap, or in its surrounding water, but in the 

 plasma itself. 



Physiological behavior of enzyms and carbohydrate transformations in 

 after-ripening of the potato tuber, C. O. Appleman {Bot. Gas., 52 {1911), 

 No. 4, pp. 306-315). — A report is given of changes observed during the apparent 

 dormancy of potato tubers, the investigations indicating that the process of 

 after-ripening is melabolic in character. In the investigations, studies were 

 made of the potato tuber in storage at 0° C. 



It was found that internal changes in the tubers are accelerated by a tem- 

 perature of 0°. Both glucose and sucrose accumulate, the sucrose increasing 

 at first more rapidly than the glucose, but at the end of 6 weeks of storage the 

 percentage of glucose was about twice that of sucrose. The diastatic activity 

 was greater in cold storage tubers than in those stored at room temperature 

 at the end of 2 to 4 weeks, but there was no appreciable difference after 

 an interval of 6 weeks. Catalase was found very abundant in potato tubers 

 stored either at 0° or at room temperatures, but it suffered a gradual reduction 

 as the storage at 0° continued. The presence of free acids would probably 

 cause this reduction, and it is believed that the behavior of catalase corre- 

 sponds with that of respiration. This is held to be significant in view of recent 



