June, 1904.] 



KNOWLEDGE e^- SCIENTIFIC NEWS. 



127 



Ba^cteria and RoLdio- 

 Activity. 



By the kindness of Pr. Al.in (irccn wc are aMe to repro- 

 duce two photot^aplis sliowins the effects that liactcria wliich 

 have been snlniiittod to the action of radium lironiidc, produce 



Tuberculosis hacilli. 



on photographic plates. Small masses of bacterial growth were 

 exposed to the li and -, rays of 10 milligramiiies of virtually pure 

 radium bromide. In a large number of inst.uiccs such masses 

 when removed from the influence of tin; radium and placed 

 between two thin sheets of glass, themselves 'not radio-active, 

 were capable of so affecting the sensitised film nf a photo- 



graphic plate with which they were brought in contact that, on 

 (levelopment in the ordinary way, the platfi showed a dark 

 area corresponding to the shape of the l)acterial mass. The 

 photo-actinic rays proceeding from the bacteria which had been 

 exposed to radimu were capable of affecting a photographic 

 plate through a double layer of lead foil. The rays thus 

 (Miiitted seem to coincide with the ;:f rays of radium, for they 

 are slopiied by a suOicieut thickness of lead. If any 7 rays 

 are emitted bv the bacteria they do not appear to affect the 

 photographic plate. It will be remembered that some years 

 ,igo Or. Johnstone .Stoney remarked that the microscopic 

 dim(Misions of bacteria might lie due to the necessity of 

 deriving their energy from the slower moving molecules of 

 substances with which llii^y were in contact, and more lately 

 il hasbfcn suggest(;d that the energy of radium might be due to 

 th(! .ni.dogous power of that element to derive ils <'uergy from 

 outside som-ces by sifting out the molecules of different speeds 

 impiTiging on it. This theory, now recciveil with Ic^ss uu.ini- 

 mity than the Kutherford-Ramsay-Soddy theory of the dis- 

 integration of the atom, is neither confirmed nor disproved by 

 Or. Al.in Creen's experiments, which appear to show thai 

 bacteria, so far as ac(|uired radioactivity iseoueerne<l, beha\e 

 like other substances. ( )ne of our jiholographs shows the 

 blur made by a mass of tubercle bacilli on a plate; the other 

 the elfect similarly produced by anthrax spores. The .acquiicd 

 radio-aclivitv lasts in some instances for over six weeks. 



A Stereoscopic Single 

 Lens. 



A Ni;\v method of obtaining stereosco|nc photographs, .and 

 stereoscopic effects when looking at them, has been designed by 

 Or. M. Von Rohr, of the Carl Zeiss firm. Its peculiarity is 

 that the effects are obtained by a single lens directed at single 



Spores of Anthrax. 



Viewing througli the Single Lens Stereoscope. 



