78 



depends on the light intensity. 1 The relation "between 

 the light intensity and the amount of carbon dioxide 

 used in photosynthesis is obvious. The faot that con- 

 siderable increases in the carbon dioxide content of the 

 air are injurious may be due to a specific harmful effect 

 of the gas but may depend merely on disturbances of respira- 

 tion by the altered oxygen- carbon dioxide ratio of the air* 



various morphological modifications which frequently 

 follow exposure to excessive percentages of carbon dioxide^ 

 are similarly inconclusive since these may be due merely 

 to alterations of food supply resulting from differences 

 in the rate of photosynthesis. That high concentrations 

 of carbon dioxide are not necessarily fatal to protoplasm 



1. Pantanelli,- Jahrb. wiss. Bot. 39_: 1G7-ES8 

 (1904). 



S. However, Deherain and Llaquerjie report tha£ 

 the respiration of leaves was unaltered in air containing 

 40 percent of carbon dioxide,- Ann. agron _. 2 : (188C). 



3. On such morphological changes see: Jentys,- 



Bu'll. Acad. Sci. Gracovie : 306-510 (189S); 



Teodoreseo,- G. R. 127 : 335-338 (189y), Rev. gen. bot. 

 11 : 445-470 (1899); Farmer and Ghandler,- Proc. Roy. 

 Soc. 0: 413-4S3 (1902). 



