INFLUENCE OF WATER 129 



to Hafenrichter,* this is not so in the two varieties, Manchu 

 and Midwest, of the soy bean examined by him. The man- 

 chu variety has a high oil and low protein content, and the 

 Midwest variety has a low oil and a high protein content. 

 It was found that the intensity of respiration of these two 

 varieties was not the same at the same temperature, nor 

 through a range of temperatures ; further, the effect of tempera- 

 ture varied at different stages of development, and is not the 

 same for each variety. According to the author, his results 

 support the view that in respiration the material to be con- 

 sumed is selected from those available for physiological com- 

 bustion. It was also observed that the seedlings when starved, 

 by continuous growth in darkness, showed a marked increase 

 in respiration prior to the complete exhaustion of the plant. 



WATER. 



Since an ordinary living plant is mostly water, it is obvious 

 that any circumstance which leads to a marked increase or 

 decrease of water may alter profoundly the expressions of 

 life ; thus if water be removed from a plant to an extent suf- 

 ficient to make the cells flaccid, growth will come to an end, 

 and therefore the respiratory activity will be ultimately con- 

 siderably lessened. This statement is intentionally qualified, 

 for an increase and also a decrease in the water supply may 

 lead to an immediate amplification in the intensity of respira- 

 tion. Maige and Nicolas f found in several instances that a 

 rise in turgescence is followed by an increase in respiratory 

 activity, and a similar result obtains, although to a lesser 

 degree, when a decrease in turgescence is brought about in 

 similar material either by natural evaporation or by the action 

 of a mildly plasmolyzing sugar solution. If a further removal 

 of water be effected by the use of a 10 to 20 per cent, solution 

 of glucose, a decrease in respiration, as indicated by a smaller 

 intake of oxygen and output of carbon dioxide, results. Smith % 

 similarly observed that vegetative organs of the snowdrop, the 

 bean, and Tropceolum, after drying in a desiccator until a 



* Hafenrichter : " Bot. Gaz.," 1928, 85, 271. 

 f Maige and Nicolas : " Rev. gen. Bot.," 1910, 22, 409. 

 X Smith : " British Ass. Rep.," 1916, 85, 725. 

 VOL. IT. 9 



