COMPARISON OF SUNLIGHT AND POINTOLITE 



43 



Again, the maximum photosynthesis of 369-1 was prac- 

 tically attained under 3000 lux, whereas the same specimen 

 gave a higher maximum of 645 under the intensity of o -40 S. 



Fig. 8. Photosynthetic Curves for identical Hydrilla plant under 

 Sunlight (S) and Pointolite (P) 



The limiting maximum is therefore not absolute but relative t 

 and depends on the intensity of the light. 



It may be urged that the C0 2 -content was in excess of 

 what could be fully assimilated under the feebler intensity 

 of Pointolite ; and that therefore the maximum under the 

 stronger sunlight was greater. The fact that the stronger 

 sunlight produces a relatively higher maximum, independ- 



