14 NEUTRON EFFECTS ON ANIIVL-ILS 



hers. Is this recovery due to repair processes on some injured cells or have 

 enough of the mother cells escaped to make a nucleus of a new accretion. 

 If they were a flock of ducks subjected to a blaze of gunshot, some may be 

 injured to recover later; some may have escaped the gunfire completely to 

 form the nucleus of a new flock. The explanation escapes us: it may be 

 one or both. 



At various dose levels a change in behavior occurs in irradiated cells. 

 At the highest dose level the result is quick death, presumably by severe 

 breakdown in the physicochemical system of the protoplasmic cells; at 

 lower levels, death results but a longer time is required for the upset of the 

 machinery of the dynamic sy;- tem of the cell. The changes may be transi- 

 tory and reversible or they maj^ be permanent where the radiation injury 

 disappears but leaves the tissue in a state of lowered resistance to further 

 radiation. There is no single type of response which can be called the 

 characteristic effect of radiation. 



Much has recently been said about the great value that the atomic bomb 

 discovery will be to the study of cancer, but does it really promise more 

 than the discovery of other destructive forces? Its only present promise is 

 to popularize the use as "tracers" of radioactive material which we have 

 been producing by the cyclotron for eight years at least. Radioactive 

 sulfur and radioactive phosphorus, the ones most useful in biological study, 

 are easy to produce; radio-carbon is more difficult. To use radioactive 

 tracers merely to tell by Geiger counters into what organ the radioactive 

 substance goes, gives little information; almost each experiment with radio- 

 tracers requires a special chemical technique in addition to get real in- 

 formation. 



Radio-phosphorus has been produced by the cyclotron and used in the 

 treatment of leukemia and polycythemia for a number of years with con- 

 siderable success. Its effects upon cancer have not been encouraging. 

 Radio-iodine produced by the cyclotron has been also used in the treat- 

 ment of certain forms of goiter with considerable effect. The atomic pile 

 may produce these substances, but they are not new. 



The real value of the new interest in radiation effects is the effort to ex- 

 plain their action in stopping the growth and division of j^oung, immature 

 cells. Cancer is a problem in cell division and cancer cells are relatively 

 immature rapidly-dividing cells. If their division can be inhibited, their 

 relatively short life and weakness will cause them to die and, if no new cells 

 are formed, the cancer will diminish and disappear. If the neutron radia- 

 tion study shows the mechanism whereby lymphocytes are prevented from 

 reproduction, the mode of prevention of cancer cell division is at hand. 

 It may then be possible to apply and produce these conditions within the 

 cancer cells, even without radiation, and so produce a stoppage of cell 

 division and growth. — And that is our aim and hope. 



