PHOTOSYNTHETIC CURVE 



35 



spring-specimens at the middle of February and the winter- 

 specimens at various times from December to January. 

 The results given by a batch of spring-specimens showed 

 remarkable agreement with each other ; the same was the 

 case with the winter-specimens. The average activity of 

 Hydrilla in spring was higher than in winter, the ratio between 

 the two being more or less definite. About twenty-four 

 different investigations were carried out, half of them in 

 winter and the other half in spring. 



Experiments with Spring-Specimens 



Observations were made of the rates of evolution of 



Fig. 7. Photosynthetic Curves under Increasing Intensity of Light, 

 for Spring-specimen s, and for Winter-specimen w 



oxygen at various intensities of light from 300 to 3000 lux. 

 Gas began to be evolved at a much lower intensity, but the 



