6 BULLETIN 149, U. S. DEPABTMENT OF AGBICULTUBE. 



have penetrated the walls of the glass tube 1 in which the polonium 

 was contained, much less could they have penetrated the intervening 

 soil which separated the tube from the planted seeds. If the experi- 

 ments were carried out as described, the seeds in the pot containing 

 the polonium tube must have been as free from any radioactive influ- 

 ence as those in the control pot, and the marked increase noted in the 

 growth of the seedlings in this pot could not have been due to the 

 presence of the polonium tube as claimed by the author, but must be 

 attributed to some other influence. 



From the way in which other experiments were carried out it seems 

 reasonable to suppose that other results were likewise incorrectly at- 

 tributed to radioactive influence. Thus it was concluded " that 

 freshly fallen rain water tends to retard the growth of roots of beans 

 (Lupinus albus) and that the effect is due to the radioactivity of the 

 water." 2 It was further observed from other experiments that "the 

 growth in length of radicles of Lupinus albus is uniformly accelerated 

 in an atmosphere containing radium emanation." 3 The intensity of 

 the radiation was not given in either case, but it was indicated, and it 

 is undoubtedly a fact, that the intensity of the radiation in the latter 

 experiment was much greater than in the former. It would thus 

 seem that as measured by the growth that takes place without any 

 radioactive influence, a weak radiation retards, while a stronger 

 radiation stimulates the growth of certain seedlings. This is con- 

 trary to experience and to the general conclusion reached by the au- 

 thor that " the rays of radium act as a stimulus to protoplasm. Re- 

 tardation of growth following an exposure to the rays is an expres- 

 sion of overstimulation. Acceleration of growth indicates stimula- 

 tion between a minimum and an optimum point." 



Experiments were also described in which seeds and seedlings were 

 exposed in a 6-inch pot to the radiation from 10 milligrams of radium 

 bromide of activity 1,800,000. A preparation of 0.5 gram of radium 

 bromide of activity 10,000 was also used. Both retarding and stimu- 

 lating effects were observed, depending on the seedlings used and the 

 conditions of the experiments. It would be expected that with a 

 radiation of the intensitj" given by these preparations a marked 

 effect would result, as was observed. The experiments are thus of 

 scientific interest, but they do not give any indication that radium 

 can be of any practical value in general farming. To duplicate the 

 experiments on a large scale would require a quantity of radium 

 which is not available. 



1 In this connection the author himself states : " I am unable to explain how physio- 

 logical effects can be obtained with radio-tellurium [polonium] in a sealed glass tube, 

 for this substance gives off only a rays, and these are not thought to be able to pass 

 through the glass walls of the tube. The results, however, were constant and decided, 

 leaving not the slightest doubt as to the physiological efficacy of the preparation." 

 Loc. cit., p. 144. 



- Loc. cit., p. ITS. - Loc. cit., p. 156. 



