282 



that the alleged growths were "nothing more than finely divided 

 precipitates of insoluble barium salts." He was unable in a 

 preparation similar to the one described by Burke, to observe 

 anything like cell-division, and believes that an occasional group- 

 ing of the particles in pairs must be pure^ fortuitous. The 

 appearance of growth of the radiobes is explained as due to dif- 

 fusion of the precipitate through the gelatine from a point of 

 concentration where the radium salt was in contact with the gel- 

 atine. Salts of barium, lead, and strontium produced effects 

 exactly similar to those caused by radium preparations. 



Again repeating Burke's experiments, Rudge^" was unable to 

 secure the radiobes when agar-agar was substituted for gela- 

 tine and distilled water was used. If tap-water was employed a 

 slight growth resulted, while the addition of a soluble sulfate re- 

 sulted in a very dense growth. An examination of 30—40 samples 

 of gelatine showed that they all contained enough HgSO^ to give 

 a distinct, sometimes a dense, precipitate with barium chloride in 

 the presence of HNO.j. This precipitate was found, on analysis, 

 to be BaSO^. Gelatine was then prepared free from sulfates and 

 gave no growth. Negative results were obtained with salts 

 of * uranium, thorium, pitchblende, and metallic uranium, thus 

 clearly indicating" that there is not the slightest connection be- 

 tween the formation of the rabiobes and radioactivity. 



A sample of gelatine from which HgSO^ had been removed was 

 sealed with a radium salt from June until September. At the end 

 of that time no growth appeared, but when a soluble sulfate was 

 added to a portion of this gelatine the growth began at once. 



"The cellular form of these precipitates," said Rudge, "is prob- 

 ably due to the circumstance that the gelatine is liquefied by the 

 action of the salt, and each particle of precipitate is formed about 

 a core of gelatine, so that the layer of barium sulfate forms a 

 kind of sac or cell which is surrounded by the solutions of the salt 

 in the liquefied gelatine. This ' cell ' may be permeable to the 

 liquefied gelatine containing a salt in solution, which, passing 

 through the cell-wall, causes an expansion to take place, the limit 

 of growth being controlled by some surface tension effect." 



No trace of a nucleus or of mitosis was observed under the 



