38Ü 



At a (emperatiire of about 17° C. some sporaiigiophores adapted 

 to exposures to J/512, J/64, 8 and 64 M.K., were darkened, the 

 growtli-nieasiirinj;; lieiiig continued. The responses of growth, con- 

 sisting in a relaidalion of growth were very characteristic. 



Tiie cardinal [mints, computed from sets of 5 — 6 experiments are 

 given in the sulyoined table. 



TABLE II. 



The reaction at 64 MK was observed in a great number of 

 observations (J9). Fi'om the results obtained a maximum after about 

 17 min. could be derived with a rate of growth of about 98^°/» o^" 

 the rate of growth in light; after that the oscillations get more and 

 more indistinct and after J'/, — 2 hours the equilibrium for the 

 growth has externallj been reached. The rate of growth appeals to 

 have become 93 7o of the rate of growth in light, with a mean 

 error of about 1 7«- 



From comparison of the above reports the contrary reactions, 

 brought about b)' making light and dark, are clearly perceptible. 

 (See the ligure). 



The divrh- and ligJit-groivth-responses of hypocotyledons 

 of Helianthus globosus. 



The light-growth-response of these organs is suiïiciently known 

 from "Ij.u.W. 11". It consists in a retardation of growth, making 

 its tirst influence felt, when exposed to 1 MK after 8 min.; the 

 minimum of 74 "/o of the rate of growth in light appears after 

 27—38 minutes, after which the growth reverts to its previous rate, 

 at least in a slight number of observations it is after 3 hours not 

 perceptibly different from the rate before exposure. 



