138 EFFECTS OF RADIUM RAYS IN THE SOIL 



March 19, 11 : 30 A. M. 



Exposed and control cultures were arranged as described in Ex- 

 periment 33, except that white mustard seeds were used. Twenty- 

 one unsoaked seeds were planted in each pot, at distances from the 

 center as follows : 



II seeds 40 mm. from the center. 



6 seeds 25 mm. from the center. 



4 seeds 10 mm. from the center. 



March 23, 10 : 30 A. M. 



Eleven of the exposed seeds have germinated, and only six of the 

 control seeds. The seedlings from the exposed seeds average at least 

 one third taller than the control seedlings, but measurements were 

 not taken. The exposed plants seem in every way more vigorous. 



Experiment 35 

 April 3, 9 A. M. 



Into each of three pots of soil were planted 12 unsoaked seeds of 

 Henderson's " First-of- All " peas {Pisum sativum), m two circles, 

 the outer one of 8 seeds 60 mm. from the center of the pan, the inner 

 of 4 seeds 30 mm. from the center. 



Into the center of the soil in the first pan was inserted the end of 

 a tube of radium bromide (10,000 x ), in the center of the second the 

 sealed glass tube of radio-tellurium, into the third an empty glass 

 tube. The lower ends of all the tubes were depressed 25 mm. below 

 the surface of the soil- 

 April 6, to: 30 A. M. 



8 plants exposed to radium rays show the arch of the hypocotyl. 



6 plants exposed to radio-tellurium show the arch of the hypocoytl. 



3 plants of the control culture show the arch of the hypocotyl. 



April 18, 10 A. M. 



The plants grown in the soil with the radium-tube are taller, and 

 in every way more vigorous looking than those of the other two pots. 

 There is very slight, if an}^, difference between the height of the 

 plants grown with the radio-tellurium in the soil and the control 

 plants. 



A count of the total number of root tubercles on the roots of the 

 plants gave a total of 18 tubercles where the radium-tube was, 19 

 with the radio-tellurium, and 22 in the control. These differences 

 are not considered significant. 



