ACTION OF IONIZED AIR 119 



varies according to the presence or absence of other sub- 

 stances : thus whilst the respiratory activity may be fifty 

 times as great as the normal under the action of a 7-5 per 

 cent, solution of ether, this high intensity is considerably 

 reduced if 0-85 per cent, of sodium chloride be added. 



According to A. C. R. Haas,* small doses of anaesthetics 

 are without result on the respiration of Laminaria, doses 

 sufficiently large to produce a measurable result effect a 

 prolonged increase in respiration, whilst strong doses result 

 in an initial increase followed by a decrease ultimately to 

 zero. In no experiment was it found that the initial effect of 

 an anaesthetic was a lowering of the respiration intensity, from 

 which it is concluded that the state of anaesthesia is not brought 

 about by the lowering of the respiration. It is clear from these 

 results that in general anaesthetics have a twofold action : a 

 small dose is a stimulant, a large dose is a narcotic. And this 

 is true not only for respiration but also for other expressions 

 of plant activity such as the circulation of protoplasm within 

 the cell. 



THE ACTION OF IONIZED AIR. 



Spoehr f was the first to observe that the respiration of the 

 plant is regularly higher in conditions which vary only as 

 regards daylight and darkness, differing, in other words, only 

 in the degree of ionization. The differences observed were, 

 however, not considerable ; in the wheat plant the ratio day 

 rate/night rate was found to be 1-042 in normal air and 

 roio in deionized air. 



StoppelJ found a 0-3 to 1-13 per cent, increase in the 

 respiration of cut shoots when supplied with air ionized 

 by passing through a tube containing carnotite, a radio-active 

 mineral. In the carefully controlled experiments of Middle- 

 ton^ barley seedlings were grown on sterilized glass wool and 

 glass beads watered with a culture solution. The culture 

 was made in a glass box and supplied with a current of air 



* A. C. R. Haas : " Bot. Gaz.," 1919, 67, 377. 

 t Spoehr : id., 1915, 59» 3°o- 

 X Stoppel : " Bot. Zeit.," 1920, 12, 1920. 

 § Middleton : " Ann. Bot.," 1927, 4'> 345- 



