WHAT IS PHYSICAL LIFE 



tions in the history of medicine have been 

 about the mechanism of Immunity, or why 

 a single attack of certain infectious dis- 

 eases renders a person immune from a 

 second attack. It was through these in- 

 vestigations that some valuable antitoxins 

 were discovered in the immunized blood 

 serum, which raise hopes that we may yet 

 find the antitoxins for the worst forms of 

 our deadly infections, just as an anti- 

 venom has been found for the cobra's 

 poison, and another for that of the rattle- 

 snake. But each of these antitoxins is 

 specific in that it does not afford any pro- 

 tection except just against its own poison. 

 This led Professor Wasserman of Vienna 

 to investigate whether the blood of each 

 kind of animal did not contain some in- 

 gredients which would be specific to that 

 animal, that is, not to be found in any 

 other animal, a fact which, if found, might 

 be of use in medico-legal cases. 

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