CHAPTER III 



PREVIOUS INVESTIGATIONS UPON ANIMALS 



The recent development of the science of the electron has so 

 unified physical and chemical phenomena that only artificial boun- 

 daries now exist between the physics of heat waves, electro-magnetic 

 waves, light waves, ultra-violet light, X rays, and the x rays of 

 radium. They differ only in degree, not in kind, and so their 

 physiological roles are unified, and effects caused by any one of 

 them throw light on the results produced by all the others. Like- 

 wise, as is well known, it is becoming increasingly difficult to draw 

 the line between physiological investigations in botany and those in 

 zoology. They both center in the common field of cell-physiology, 

 so that very often results obtained with plants can be adequately 

 interpreted only in the light of investigations made with animals, 

 and vice versa. 



For these reasons it has seemed best to include, in the following 

 historical review, the literature dealing with the effects, not only of 

 radium rays, but of X rays and of ultra-violet rays as well on both 

 animals and plants. The results of the studies of the physiological 

 and therapeutic effects of X rays were brought together by Schiff '"^^ 

 in 1901, and no attempt is here made to compass the voluminous 

 literature bearing on X ray therapy and radium therapy. 



In 1899 Schaudinn^*^' announced that the various protozoa react 

 differently to the stimulus of Rontgen rays ; certain species do not 

 react at all, some only slightl}', and still others very strongly. The 

 dissimilarity in reaction appears to be connected with differences in 

 the structure of the protoplasm. Those which react quickly possess 

 a looser plasm than those which react slowly or not at all. 



The now familiar fact that radium rays will cause a painful 

 " burning " of the skin was first recorded by Walkhoff,*' in October, 

 1900. This effect was noted in the same year by Giesel,^^ who laid 

 a double walled celluloid capsule containing 0.27 gr. of radium- 

 barium bromide for 24 hrs. on the inner surface of his arm. The 

 first effect noticed was a slight reddening of the exposed region, and, 



43 



