264 



SCIENCE 



[N. S. Vol. XXV. No. 633 



emanation, an inert gas of the argon family, 

 which is radioactive, and whose atoms are, 

 therefore, undergoing a disintegration. 



Recent researches lead to the conclusion 

 that the phenomenon of radioactivity is not 

 confined to the so-called radioactive ele- 

 ments, radium, uranium, thorium and 

 others, but is a general property of matter. 

 Not only are the heavier metals, such as 

 lead, zinc, silver, but various other sub- 

 stances, namely aluminum, copper, tin-foil, 

 air from soil, spray at the foot of water- 

 falls, mud, tap water, petroleum, freshly 

 fallen rain and snow, metal surfaces on 

 which light waves of short wave length 

 impinge, and flames, have all been found 

 to give off a penetrating radiation. It 

 seems probable that radioactivity is a gen- 

 eral property of matter. Results already 

 obtained demonstrate conclusively that it is 

 a factor in the normal environment of 

 living thingSj and its effect on the life proc- 

 esses of plants becomes, therefore, a matter 

 of considerable interest and importance. 



Some Effects of Radioactivity on Plants: 



C. Stuaet Gager, New York Botanical 



Garden. 



In ascertaining the effects of radioactiv- 

 ity on plants, it has not been possible satis- 

 factorily to screen out the various kinds of 

 rays, and the emanation, so as to study 

 separately the effects peculiar to each. The 

 results obtained, therefore, must be attrib- 

 uted, almost without exception, to the sum 

 total of all three kinds of rays involved in 

 the radioactivity of radioactive substances. 

 The present paper concerns chiefly the re- 

 sults obtained with radium bromide, of 

 various strengths of radioactivity, used 

 either in sealed glass tubes or in the form 

 of Lieber's radium coating on rods and 

 cylinders. 



Experiments lead to the conclusion that 

 the rays of radium act as a stimulus to the 

 physiological processes of plants, accelera- 



ting, retarding, or inhibiting, either ger- 

 mination, growth, respiration, fermenta- 

 tion, cell division, starch formation, sensi- 

 tiveness to gravity, according to the 

 strength of the radium salt employed, the 

 duration and distance of exposure, the in- 

 tervention of screens, the nature of the tis- 

 • sue and, possibly, the species of the plant. 



When the pollen or the ovary is exposed 

 before pollination, or the ovary after fertil- 

 ization, the resulting seeds produce plants 

 profoundly different in the first generation 

 from that normal for the species. If these 

 modifications shall prove heritable in sub- 

 sequent generations the ability of radium 

 rays to induce mutative changes will have 

 been demonstrated. 



While there is seemingly a very crude 

 analogy between radioactivity (atomic dis- 

 integration) and the molecular disintegra- 

 tion involved in destructive metabolism, 

 there is nothing in the former that may be 

 rightly compared, in any way, to con- 

 structive metabolic processes. The results 

 of continuous experiments, covering a pe- 

 riod of over two years, do not give the 

 slightest support to any theory that radio- 

 activity is, in any real sense, comparable 

 to metabolism, or that the rays of radio- 

 active substances are capable, independent- 

 ly, of elevating inorganic compounds into 

 the condition of living organisms. 



The Pathology of the Bice Plant: Haven 

 Metcalp, U. S. Department of Agricul- 

 ture. 



The literature on rice diseases is scanty, 

 and mostly in the Italian, Japanese, Dutch, 

 Russian and Portuguese languages. Fif- 

 teen diseases have been described on rice^ 

 further research may be expected to dem- 

 onstrate the identity of several of these, 

 now supposed to be distinct. Eight rice 

 diseases occur in America, of which six 

 were described by the writer in Bulletin 

 121 of the South Carolina Experiment Sta- 



