MISCELLANEOUS EXPERIMENTS 183 



abundant gemmae, while as yet there are no signs of cupules on the 

 control plants. 



Experiment 6i 



A sealed glass tube of RaBr2 (lo mg. ; 1,500,000 x) was placed 

 in contact with the gemmae in a cupule of Lunulart'a for six days. 

 The gemmae were then sown on one half the surface of soil in a pot. 

 The other half of the surface was sown with unexposed gemmae. 



Fourteen days later the unexposed gemmae are developing thalli, 

 but those exposed have not grown at all, and are evidently dead. 



This experiment was repeated, the exposure to the radium-rays 

 being for 19 hours. At the close of the experiment, 42 days after 

 the exposed and the control gemmae were sown on soil, none of the 

 radiated gemmae have grown, but all of the control set have devel- 

 oped vigorous thalli. 



Experiment 62 

 April 3, 9:45 A. M. 



In order to see if the growth of gemmae of Lunularia would be 

 affected by the presence of a tube of radium in the soil, 1^6 gemmae 

 were sown on the surface of soil in a flower pot, and a tube containing 

 10 mg. of RaBrg of 1,500,000 activity was inserted verticall}^ into 

 the soil at the center of the pot, the end containing the radium being 

 25 mm. below the surface. 



Control culture with 36 gemmae, but empty glass tube. 



May 5, 2 :30 P. M. 



The gemmae are growing well in both cultures, with no appre- 

 ciable difference in the two sets. 



May 12. 



There is no significant difference in the size of the developed 

 thalli in the two cultures. The radium tube was removed. Duration 

 of exposure 5^ weeks. 



June 2, 10 A. M. 



The thalli in the control culture are much larger and healthier 

 in appearance than those exposed, and have well developed cupules 

 with genimae, while cupules have scarcely begun to develop at all 

 on the radiated plants. 



