CHAPTER XI 



EFFECTS ON PLANT GROWTH: MISCELLANEOUS 

 EXPERIMENTS 



It is clearly recognized that in the preceding experiments a rather 

 narrow range of plant material was employed. In the following 

 miscellaneous experiments a greater variety of material was used. 



Experiment 55 



In order to test the effect of the rays of radium on the germination 

 of pollen grains, ten pollinia of Asclepias curassavica were placed 

 to germinate in a moist chamber on slices of beet, at varying dis- 

 tances from a sealed glass tube of RaBrg of 7,000 activity. Control 

 of ten pollinia, similarly arranged, but with no radium. 



Within three hours the three pollinia nearest the radium tube 

 had begun to germinate, but there were no signs of germination in 

 the control set, and the experiment was closed. 



Experiment 56 

 March 10, 10 : 30 A. M. 



In order to test the effect of radium rays on the form and rate of 

 growth of yeast {Sacchat'omy ces)^ a small portion of a Fleischmann's 

 compressed yeast cake was mixed in a 5 per cent, solution of sucrose. 

 The liquid was then divided, and one half placed in a small glass 

 dish, the other half in a similar dish. In the former was placed the 

 radium tube of 10,000 activity, supported vertically by a cork cover- 

 ing the dish, and with the end holding the radium extending to the 

 bottom. In the other dish was similarly placed an empty glass tube. 



March 11, 3 : 30 P. M. 



There is no apparent difference in the microscopic appearance 

 of the yeast contained in the drops that adhered to the tubes as they 

 were withdrawn from the liquid in the two dishes. 



March 12, 11 : 15 A. M. 



The yeast cells seem to be rather more numerous in the radium 



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