412 PROTOPLASM 



Radium does kill tissue and retard the growth of cells, and young 

 (cancer) cells are more sensitive than old ones, but one cannot 

 be certain that all cancer cells receive the emanations. In any 

 case, the cancerous growth is retarded, and life usually prolonged 

 somewhat by treatment. 



Hereditary changes similar to those caused in plants and 

 animals by radiation with X rays have also been produced in 

 part by radiation from radium. Especially interesting is the 

 work of Babcock and Collins, who allowed fruit flies to breed in a 

 locality where there was fully twice the natural earth radiation 

 that existed in the laboratory. ■ Such flies develop a tendency 

 that causes the males before hatching to die twice as often as 

 do normal flies. From this we may, with some justification, 

 conclude that radioactive mineral deposits lying near the surface 

 of the earth affect the course of evolution. 



Cosmic Rays. — ^Lastly come the cosmic rays, too new in our 

 knowledge of radiation yet to have been put to use. But pre- 

 dictions as to their influence on life have already been made. 

 John Joly suggests that as young and cancerous tissue appears 

 to be more sensitive to gamma, and therefore probably also to 

 cosmic, rays than is normal adult tissue, it is possible that our 

 bodies are kept relatively free from cancer by the bombardment 

 of the rays which they are constantly receiving. Should this 

 feature of our radiation environment be lessened, as it may be 

 during certain (rhythmic) periods, then such times would be 

 ones of increased cancer growth. The speculation is highly 

 imaginative, but who can deny the possibility of some truth in 

 it? Twelve cosmic rays a second strike our bodies (at sea level). 



We thus see that experimental evidence is overwhelming in 

 support of the hypothesis that the evolution, development, and 

 well-being of plants and animals are associated with and in great 

 measure dependent upon their natural radiation environment. 

 To this can be added the internal environment of tissues, with 

 its content of radioactive elements such as potassium and 

 rubidium. 



LIVING MATTER AS A SOURCE OF RADIATION 



So far, we have considered the influence of our radiation 

 environment upon life. Let us now consider living vmatter as a 

 source of radiation. 



