PREVIOUS INVESTIGATIONS UPON ANIMALS 5 1 



with their rapidly dividing cells, may possibly depend upon the same 

 property of the rays. If the exposure of the animals was not too 

 prolonged they recovered. Thus, rapidly creeping specimens of 

 Amoeba Umax and Pelomyxa palustris came to rest and contracted 

 after an exposure of three to four hours. In this condition they lay 

 unchanged for 24 hours, but if the radium influence was then with- 

 drawn they revived completely, and crawled about normally after 

 two hours. Dr. Zuelzer's results were confirmed the following year 

 by Hussakof,^" who states that from one to two hours exposure pro- 

 duced no effect upon amoeba and paramecium. 



The experiments of Berg and Welker^ on the metabolism of 

 young dogs led them to the conclusion that: "Radium preparations 

 of low activity (240, 1,000, 10,000) containing barium bromide in 

 preponderating proportions were without special influence on metab- 

 olism when administered per os or subcutaneously in relatively large 

 quantities. Equal or larger doses of pure radium bromide also failed 

 to show any decisive effects before fatal results were inaugurated." 



The effect of prolonged exposure to radium of weak activity was 

 studied by London. ^^-^^ He does not give the activity of his prepara- 

 tion, but rabbits were exposed to 260 mg. of it for 14 months with 

 injurious effects both to external and internal organs. The electric 

 organ of the torpedo was exposed by Mendelssohn^^ to rays from 3 

 mg. of radium bromide of 1,800,000 activity in a glass tube. No 

 effect was observed until the end of the first hour of exposure. 

 Then, after a period of 20-30 minutes of stronger activity, there took 

 place a gradual weakening of the discharge, which fell to a minimum 

 in five to six hours. This enfeebled discharge continued for six to 

 eight days, but no complete suppression of the function of the elec- 

 tric organ of the torpedo, due to the radium rays, has been observed. 



In 1906 Meyer ^^' ^^ ascertained that, " By whatever channel radium 

 is introduced (into the animal body) it seems to find its way into prac- 

 tically all the fluids of the body," and in 1907 Bardeen^ demon- 

 strated that, when the ova of toads were fertilized by spermatozoa 

 that had been previously exposed to the X rays, the ova developed 

 abnormally. Similar results were obtained later in the same year ^ 

 with Rana piptens, and the least abnormal and longest survivor out 

 of 250 larvae, died one week after the eggs were^fertilized. 



The coagulation of albumins by the actions of ultra-violet light 

 and of radium was studied by Dreyer and Hanssen.^^-^^ They found 



