THERMOTROPISM IN ROOTS 



149 



7" registered 37°C. and T"" 14°C. for the first seven hours. Later both allowed 

 to equal room temperature, 15°C. Number VI was very slightly bent to one side 

 after six and one half hours. Several roots were bent the next morning after a total 

 of twenty-three and one-half hours, but this could not have been due to thermo- 

 tropism, first because there was no regularity and secondly because the temperature 

 difference was not maintained. 



Experiment VI. 



Eight roots of Pi sum sativum 



Number VI represents the only case in all these experiments of what might be 

 called a negative thermotropic reaction. All the other roots remained straight, 

 7" registered 3S°C. and T'" 13°C. Number VII did not grow at all. 



