The Action of Radium on Growing Cells. 141 



Wedd, 1 who discovered mitoses six days after the irradiated grafts 

 had been implanted. 



The preliminary experiments now to be reported do not wholly 

 clear up these conflicting statements, and it is certain that a great 

 deal more work must be done on a great variety of tissues with 

 carefully measured quantities of radium and standard screening 

 before we can obtain any insight into the effects exerted by this 

 substance. We have noted, however, that 155 mgm. of radium 

 bromide, screened with 1 mm. of aluminum and 0.18 mm. of 

 coverglass, did not stop the beating of embryonal heart tissue in 

 vitro, nor check a profuse outgrowth of connective tissue from the 

 mass, after an exposure of three hours. So, too, the Flexner rat 

 carcinoma, growing in rat plasma, when treated with 155 mgm. 

 of radium bromide, screened with 0.4 mm. brass and 0.18 mm. 

 coverglass, was not entirely inhibited in its growth by a three 

 hours' exposure, though the amount of radiation was three times 

 that used by von Wassermann. 



In another series of the same tumor, however, growth was 

 inhibited after an exposure of three hours to 155 mgm. of radium 

 bromide, screened with 0.8 mm. of brass and 0.18 mm. of coverglass 



These absolutely contradictory results, representing a con- 

 siderable series of experiments, show how cautiously we must draw 

 conclusions as to the action of radium on cells when they are placed 

 in unfavorable surroundings. 



The growth of the Jensen rat sarcoma was inhibited, but not 

 stopped, by an exposure of three hours to 30 mgm. of radium 

 bromide, screened with 0.8 mm. of brass and 0.18 mm. of cover- 

 glass, while an exposure of three hours to 155 mgm. with the same 

 filter stopped all growth. In this case, apparently, the sarcoma 

 was more susceptible to radium than the carcinoma, while em- 

 bryonal tissue was the most resistant of all. Similar differences 

 were noted by Menten in radiating transplanted tumors. The 

 same tumor tissue in vivo when exposed to radiation of far greater 

 intensity is uninjured, as shown by its transplantability. 



In conclusion, then, 155 mgm. of radium bromide, screened 

 with 1 mm. of aluminum or 0.8 mm. of brass and only about 1.5 



1 Arch. Middlesex Hospital, 1912, XXVII, 50; see also Russ and Chambers, ibid., 

 1913, XXX, 120. 



