372 BOTANICAL GAZETTE [OCTOBER 
intermittent carbon dioxide treatment was apparently about 
optimum for the development of the roots of this plant. 
Fic. 8.—Phaseolus vulgaris subjected to different carbon dioxide treatments: 
pot at left received no carbon dioxide treatment, one in middle received 8 hours’ 
treatment daily, one at right constant carbon dioxide mabe, 
Fic. 9.—Roots of plants shown in fig, 8: 2 at left no carbon dioxide treatments, 
> 
2 in middle 8 hours’ carbon dioxide treatment daily, and 2 at right constant carbon 
dioxide treatment. 
