10 MISSOURI AGR. EXP. STA. RESEARCH BULLETIN NO. 21 



the winter. Fisher's 1 investigations well illustrate this transforma- 

 tion. In autumn, the parenchyma is filled with starch. During late 

 autumn the starch is transformed to fats and, in part, to glucose. 

 In some cases this change occurs in the cortex only, the starch in the 

 remaining tissues being unchanged; in other cases, no starch can 

 be found during midwinter. Starch is reformed during early spring, 

 and soon reaches a maximum equal to that of the 'previous autumn. 

 When the buds open the starch is again dissolved to be used in build- 

 ing up new tissues. The reserved food in the buds also undergoes a 

 marked change. Part is transferred to the embryonic organs which 

 at first were free from starch. Quantitative analyses of Castanea 

 wood made by Leclerc du Sablon substantiated these observations. 

 This investigator found that the sugar content in October was 2.2 

 per cent. By February it had increased to 4.3 per cent. A month 

 later the quantity of sugar was again reduced to 2.7 per cent. Chan- 

 dler 2 found the greatest amount of dextrose in apple twig sap in 

 December. The sap becomes poorer and poorer in sugar until in 

 May. 



Since reproductive and chemical activities continue to take place 

 in resting plants, it might be expected that they also respire. The 

 experiments to be described in succeeding pages of this report throw 

 considerable light on the normal as well as stimulated respiration. 

 In general, the respiratory activity in plants is diminished during 

 the resting period, but CO 2 production continues to go on at all 

 times. Hence it may be said that the rest period is not a stage of 

 complete inactivity as many physiological functions continue. Their 

 activity, however, is reduced and is also dependent upon external 

 conditions to some extent. 



RESPIRATION EXPERIMENTS 



It has been known for some time that anesthetics and " poisons" 

 in general stimulate the respiratory processes of plants. Likewise 

 mechanical injury, high temperature and other agents are known 

 to bring about greater CO 2 production. This is true of resting as 

 well as active tissue. 3 



1. Fisher, A., Beitrage zur Physiologic der Holzgewachse. Jahrb. f. wiss. 

 Bot. (1891) 22, pp. 60-73. 



2. Chandler, W. H., Sap Studies of Horticultural Plants. Mo. Agr. Exp. 

 Sta. Research Bui. 14. 



3. Simon, S. Untersuchungen iiber das Verhalten einiger Wachstums 

 funktionen sowie die Atmungs tatigkeit der Laubholzer wahrend der Ruhperiode 

 Jahrb. f. wiss. Bot. 43 (1906) pp. 1-48. 



Iraklionow, P. P. Ueber den Einfluss des Warmbads auf die Atmung u. 

 Keimung der ruhenden Pflanzen. Jahr. f. wiss. Bot. 51, pp. 515-540. 



Butler, O. A Note on the Significance of Sugar in Tubers of Solatium 

 tuberosum. Bui. Torrey Bot. Club 40 (1913), p. 110. 



