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INFECTION. 133 
young. On the other hand, animals vaccinated with 
cowpox have not been found to have immune offspring. 
Toxins injected into the parents apparently do not pass 
the placenta; but antitoxins do, giving thus a slight 
transitory passive immunity. A slight immunity is 
also given by immune mothers through their milk, a 
smal] amount of antitoxic substance being absorbed. 
