AGRICULTURAL BOTANY. 127 



developed normally. lu later experiments when Ki'own in solutions containing 

 10 per cent saccharose, cress made no more growth than it did in cultures where 

 0.5 per cent glucose was added. When grown together hi the same media, both 

 radishes and cress made good growth. From this fact the author concludes 

 that cress can take up only invert sugars through its roots. Radishes are able 

 to take up saccharose and invert a considerable portion of the sugar, which 

 could then be utilized by the cress. 



Carbon dioxid transportation in leaves, K. Zijlstra (Kohlensduretransport 

 ill liluttcni. Imtiig. Di>is., Univ. Groningcn, 1909, pp. 128, pis. 2, figs. 3). — By 

 means of specially devised ai)paratus, the author studied the transportation of 

 carbon dioxid through leaves. Portions of the leaves of a considerable number 

 of species of plants were exposed to carbon dioxid while the other parts were 

 kept in atmosphei-es free from that gas. Different illuminations were also 

 given to parts of the leaves and the movement of starch traced. 



In all cases it was possible to show a transportation of starch. In wheat it 

 was carried for at least 2.5 cm., in Acorus 1.25 cm., in the dahlia 0.5 cm., and in 

 the walnut, horse-chestnut, and linden leaves about 2 or 3 mm. 



The temperature of respiring- plants (Gard. Chron., 3. scr., Ifo (,1909), No. 

 1161, p. 200). — A review is given of some recent investigations by Peirce and 

 Molisch on the temi)erature of respiring plants. 



Peirce has recently shown (E. S. R., 20, p. 734) the value of Dewar flasks 

 for use in determining the rising temperature due to the respiration of seeds, 

 peas giving an increase of temperature from 17° C. to a maximum of 56° in 8 

 days. 



In the experiments of Molisch cited, leaves of different trees were used, pre- 

 cautions being taken to prevent any loss of heat by radiation. It was found 

 that the temperature within the mass of leaves rose rapidly, in the course of 12 

 to 15 hours the temperature of apple leaves rising to 59° C, hornbeam 51.5°, 

 and linden 50.8°. The leaves of a number of other plants, particularly ever- 

 greens, gave less striking results. 



In both experiments there is said to have been no question of any fermenta- 

 tion, the action being simply that of the normal respiration. In the experi- 

 ments of Molisch. when the experiment was stopped before the highest tempera- 

 tures were reached, the leaves upon examination were found to still be alive 

 and fresh. 



The respiration of plants at temperatures below zero, N. A, Maksimov 

 {Trav. Hoc. Imp. Xat. ^7. Prtcrsh.. l<(rt. Bot.. 31 {1008), III, Xo. 1, pp. 23-31, 

 dgma. 2). — The fluctuation of the respiration of pine needles, leaves of mistletoe, 

 and buds of spirjea during the winter was investigated, and it was found that 

 the I'espiration rose and fell with the temperature, but did not cease entirely at 

 the lowest temperature observed, —20° C. With the falling of the temperature 

 to zero, the respiration fell off very sharply. Between and — 12° the respira- 

 tion of the pine was 1/25 and for spirsea 1/100. 



Experiments in the freezing of plants, N. A. Maksiaeov (Trav. Soc. Imp. 

 Nai. St. Petersb., Sect. Bot., 37 (1908), III, No. 1, pp. 32-J,6, dgm. /).— Experi- 

 ments were conducted with AspcrgillKS iiigrr to determine the efl'ect of increas- 

 ing the osmotic pressure of the nutrient solution on the freezing of the mycelium. 



It was found that the mycelium would freeze before there was any formation 

 of ice either within the mj-celium or in the nutrient solution. The death of the 

 cells followed their cooling to the temperature of the surrounding medium, and 

 this cooling is said to be a secondary cause of death. By increasing the con- 

 centration of the nutrient solutions through the addition of glucose or glycerin, 

 the death of the cells due to cold was retarded but not wholly prevented. There 

 did not appear to be any definite relationship between the lowering of the tern- 



