THEORETICAL CONSIDERATIONS 269 



biogen molecule, or on the living matter of the embryo, on the 

 food substances stored in and around the embryo, or on enzymes 

 present in the seed, or on any two or all four of these factors. 

 The molecules of the biogens, of the food, or of the enzymes may 

 be shattered and utterly destroyed, either wholly or in part, or 

 the rays may onl}^ hasten metabolic processes in such a way as 

 either to accelerate germination in the active seed, or to cause a 

 premature ageing and ultimate death in the resting seed. If only 

 a peroxydiastase or other enzyme, normally present in the resting 

 seed, were destroyed it is possible that the embryo, even if it were 

 still alive, would not be able to reproduce the ferment fast enough to 

 supply the needs arising with the imbibition of water and the re- 

 awakening of the protoplasts. Or again, the molecules of the stored 

 food might be so altered as not to be capable of being acted on by 

 the enzyme. 



How do radium rays affect solutions, starch, oil, aleurone, enz3'mes 

 and other substances stored in seeds? Until these questions are an- 

 swered we cannot expect much light on the way in which the rays 

 affect resting and dry seeds. 



Studies that have so far been made of the effect of radium rays on 

 solutions have yielded contradictory results. Soon after the discovery 

 of Rontgen rays, Thomson^' (1896) ascertained that, when these rays 

 pass through a dielectric, they make the latter, during the time of 

 their passage, a conductor. All substances, he says, when trans- 

 mitting them, are conductors of electricity. "The passage of these 

 rays through a substance seems thus to be accompanied by a splitting 

 up of its molecules, which enables electricity to pass through it by a 

 process resembling that by which a current passes through an elec- 

 trolyte." The experiments of Graetz,'^' four years later, led him to 

 believe that radium rays act in a similar way, while the experiments 

 of M. Curie, •^'* in 1902, clearly indicated that both radium and X rays 

 act on liquid dielectrics as on air, communicating to them a certain 

 conductibility. The investigations of Henning,'- and of H. Bec- 

 querel,^^ led to the same conclusion. If X rays have such a property, 

 then we should theoretically expect radium rays to possess it as well. 



Kohlrausch,^^ however, concluded, in 1903, that such effects, if 

 they exist at all, were to be attributed, not to the ionizing effect of 

 the rays, but to their accelerating effect on the dissolving of the 

 glass of the resistance vessel. Later, he and Henning" found that 



