quickly became root-bound and had to be successively trans- 
ferred to larger pots. 
A most extensive series of experiments has been carried on 
at Joachimsthal by Dr. Julius Stocklasa, Director of the Chem.- 
tember, 1913. ere were many series of experiments. In one 
set, the plants were grown in ordinary soil and watered with 
water possessing various degrees of radio-activity. In another 
set they were grown in water supplied with plant food similarly 
charged, while in another set radio- active earth was employed. 
C 
rst experiments were direea toward ascertaining the 
effects of radium upon the activity of those bacteria which t 
nitrogen from the atmosphere and fix it in the soil in the ‘oa of 
plant food, thus enriching the soil. He found that liquids 
than without it. Unused soil gained from 10 per cent. to 30 
any previous experimenters had reported that radium 
exerted a toxic action on plant life, while others had declared 
to the contrary. Stocklasa repeated all these experiments, b 
in two series, one with very small amounts, the other with large 
amounts of the radium. He found that in most of the latter 
cases the effects were an while in the former they were health- 
fully stimulating. o found that different plants differed 
so materially i n thei i cep that the same amount of 
radium might be stimulant to one e but toxic to another. What 
ev more interesting and important, he showed that 
families of plants manifested this difference. 
a very low radium activity was employed, the germina- 
tion of seeds was increased from 70 per cent. to 130 per cent., 
a 
two sets of plants after 48 days of growth, one set grown under 
