162 



GROWTH OF PLANTS 



monoxide ^^ showed root-inducing effects on many plants. The paper 

 reporting these results was awarded the A. Cressy Morrison Prize in Experi- 

 mental Biology in 1932 by the New York Academy of Sciences. Later /^ 



Figure 62. Nicotiana tabacum (Turkish variety) exposed to one per cent carbon mon- 

 oxide gas. A, Control plant kept in Wardian case. B, Plant exposed to gas 15 days, then 

 allowed to stand in air two days, after which time it was photographed. C, An enlarge- 

 ment of the rooting region of B. D, Tobacco cuttings from control plants in Wardian 

 case for 10 days. Photographed 5 days after having been placed in rooting medium. 

 E, Cuttings from plants treated with one per cent carbon monoxide for 10 days and then 

 placed in rooting medium for 5 days, after which time they were photographed. 



