12 



THE FOUNDATION 



Part I 



Fig. 2.2. Chemical energy stored in a globule of fat. Fat cells from connective 

 tissue underlying the skin of a rat. Fat stained black. (After Maximow. Courtesy, 

 Gerard: Unresting Cells. New York, Harper & Bros., 1940.) 



uranium had fogged photographic plates protected by light-tight envelopes. 

 He coined the word radioactive to describe the activity. In February of the 

 next year Henri Becquerel read a paper before the Academy of Science in 

 Paris in which he announced that compounds of uranium were able to affect a 

 plate through an envelope that was proof against light. The radiations were 

 called x-rays because they were not understood. Following Becquerel's dis- 

 covery his one-time student, Marie Curie, succeeded in isolating minute quan- 

 tities of two highly radioactive new elements from uranium minerals, to which 

 she gave the names polonium and radium. In 1899 Becquerel showed that the 

 rays from uranium could be separated into two types, alpha rays easily ab- 

 sorbed by a few sheets of paper, and beta rays able to penetrate thin alumi- 

 num. In 1900 Villard discovered still a third and more penetrating radiation 

 from uranium minerals, the gamma rays. By 1913 Rutherford and Soddy had 

 coordinated the various processes and proposed a theory that the nucleus of 

 the atom was spontaneously disintegrating. They suggested that the nuclear 

 disintegration was explosive and showed that during the process particles of 

 matter and energy were lost. Since that time the knowledge and use of atomic 

 energy have become important in many fields of biology; x-ray photographs 

 are routine items in medical practice; exposure to controlled quantities of 

 x-rays is a common treatment of cancer; Muller's experimental radiation of 

 fruit flies produced inheritable differences in generation after generation of 

 their offspring; and the use of radioactive tracers has opened a new era in 

 biological investigation. 



Atomic energy is now a tool in world politics; perhaps it is more true that 



