326 Profs. Percy Frankland and Marshall Ward. 



Dark. 



at without protecting the eyes. One culture was under an ordinary 

 bell-jar exposed to light, the other under a similar bell darkened with 

 black paper, the thermometer bulbs being placed in the cavities 

 of dummy cells, arranged as the culture cells in each case. 



It would have been possible here to suppose that the light actually 

 favoured the growth if other facts were not known. 



By an accident, this filament was lost, and another (in the same 

 cell) had to be selected for the continuation of the observations, 

 which were resumed without any serious interference with the con- 

 ditions at 3.13. The following are the results : 



Dark. 



Here it is probable the rise of temperature in the lighted cell was 

 responsible for the enhanced growth ; and it may be concluded that 

 if the light of this hazy day had any inhibitory effect, it was more 

 than covered by the stimulus given to the organism by the heat-rays. 

 It is by no means to be concluded with certainty that no inhibition 

 occurred only that none could be observed during the comparatively 

 short period in which measurements are possible owing to the com- 

 plication referred to. 



