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calls attention as the real import of the phrase that " practice 

 makes perfect"? Smokers, for instance, know that they 

 have overcome the nausea of the first mild cigar, and edu- 

 cated the cells of which they consist into the enjoyment 

 even .of strong Havanas. It would seem as though in nature 

 no experience fails to leave its impress and its influence. 

 When we consider how minute is the germ, even of the most 

 intelligent vertebrate, which reproduces not only the specific 

 form and structure of the parent, but its instincts and — 

 excepting perhaps man^the influence of the experience of 

 its ancestors, it cannot seem too wonderful to suppose that 

 the protective influence of vaccines may be due to the oper- 

 ation of the same mysterious principle, and that the 

 discoverer of the physical cause of protective vaccination 

 will discover the nature of memory and heredity. Such 

 a problem may well be insoluble, and the scientific man, 

 like the Athenians of old, may have to content himself 

 simply with the recognition of the existence of the unknown; 

 but there is no more reason for discrediting the facts of 

 protective vaccination because they are beyond explanation, 

 than there would be for discrediting the facts of memory, 

 heredity, or life itself Reasoning from analogy, there is a,n 

 inherent probability in protective vaccination. Reduced to 

 its ultimate expression, animated nature would appear to 

 consist of Bufibn's organic molecules plus the principle of 

 organic memory, as inorganic nature is inert matter lolufi the 

 principle of motion. 



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J L I E R A R Y , 



