﻿ßl 273 



1) The exciting phase, which is produced hj' small doses used for exposures of 

 short duration, and in which the processes which take place normally are ac- 

 celerated, this being not only demonstrated as regards the metabolic processes but 

 also with regard to germination and growth. 



2) The narcotic phase proper, which is produced by small doses of protracted 

 experimental-periods, and by enlarged doses of short duration, is characterized by 

 the normal processes being retarded; this phase has been demonstrated as to growth, 

 germination, COo-assimilation, respiration, the condensatory processes characteri- 

 stic of the ripening process, the hydrolytic processes characteristic of the germina- 

 tion e. t. c. 



3) Large doses or averagely large doses used for exposures of long duration 

 produce "the toxic phase", which demonstrates all the phenomena characteristic 

 of death: cessation of the respiratory process, of growth and of germination to- 

 gether with a considerable destruction of substances, all the constructive processes 

 being arrested. 



Between the doses which produce an acceleration and a retardation of the 

 normal processes a neutral dose may be found (the strength of which varies with 

 the duration of exposure) the effects of which mutually annul one another: cfr. 

 this paper p. 56 No. 4 with regard to the diamino-acids, and Johannsen 1897, 

 p. 40 No. 11 compared with No. 9 and 6, as regards the nitrogenous compounds 

 and No. 5 as regards the sugars. The effect of this dose is illustrated in the figures 

 A, B, C by the first point of intersection between the curve and the X-axis. 



If the effects produced by the narcotic phase have an inverse direction of 

 those affected by the toxic phase (as illustrated in B and C) a dose may be found 

 between the toxic ones and the narcotic ones, which produces apparently no effect* 

 on some of the metabolic processes, for instance the nitrogenous compounds, while 

 it affects considerably other processes, for instance the respiratory process cfr. 

 p. 22 III 3 compared with III 3 p. 18. It is however matters of course that the 

 amounts of such "neutral" doses (as well as of all other doses which are employed 

 to produce certain effects) varies with temperature, duration of exposure, the 

 character of the processes in question, the plant objects e. t. c. e. t. c. 



' This phenomenon is indicated by tlie second point of intersection between tlie curve and tlie 

 X-axis in Figs. B and C. 



Laboratory of Vegetable Physiology. 

 University of Copenhagen. 



Dec. 1910. 



