SUNSHINE AND LIFE 83 



education with sufficient insight and patience, may 

 enable us to make them serve where they now are 

 masters. 



The remarkable discoveries on the modification 

 of the disease-producing properties of certain 

 bacteria by sunshine may perhaps encourage the 

 idea that we are making some progress towards 

 the attainment of this desirable millennium. That 

 diminution of the virulence or disease-producing 

 power of such deadly microbes as those of cholera, 

 anthrax, and tuberculosis can be brought about 

 through simple exposure to the sun's rays seems 

 almost inconceivable, yet it has been discovered 

 that by placing the cholera bacillus, for example, 

 in the sunshine its virulent character undergoes 

 such a profound modification that it is actually 

 reduced to the condition of a vaccine, and may be 

 employed to protect animals from infection with 

 its still virulent brethren. Yet this is what has 

 been undoubtedly shown by Dr. Palermo in very 

 carefully conducted investigations. He was, more- 

 over, able to indicate, within a very narrow margin, 

 the precise amount of insolation necessary to bring 

 about this result : for if the cholera cultures were 

 only exposed for three hours, their toxic properties 

 were not reduced to the condition of vaccine ; but 

 if the insolation was continued for three and a half 

 hours up to four and a half hours, they became 



