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epidemic cerebro-spinal meningitis. Are these, or any of 

 them, subject to the influence of heredity ? Before attempt- 

 ing to answer this question, I may be permitted to mention 

 the now generally-believed doctrine that the acute infectious 

 diseases are dependent for their production upon a contagium 

 or miasma vivum ; in other words, upon specific germs which 

 have the power of reproducing themselves to an unlimited 

 extent, the specificity of which consists in the fact that a 

 given form or kind of disease is invariably, absolutely, and 

 under all circumstances, due to a given kind of morbific 

 germ, as cause or agent. We thus see that at any rate, in 

 the majority of the acute infectious diseases the body 

 remains passive to the action of germs, virus, or poison 

 intruded from without ; and that the autochthonous origin 

 or spontaneous generation of the contagium vivum is no 

 longer generally recognised or admitted. When we therefore 

 regard the fact that any of these specific germs or poisons 

 may so disturb the health of an infected individual as to not 

 only cause him intense suffering, but to jeopardise his life ; 

 that after a longer or shorter time these effects may cease 

 completely, and, beyond the life-long immunity from the 

 influence of the same poison thus produced, the body may 

 be otherwise unmodified, we cannot expect to find much 

 evidence of the influence of heredity, especially as even the 

 immunity of the individual cannot be transmitted to any 

 great extent. Doubtless, these specific fevers, or, at least, 

 some of them as, for example, measles and small-pox 

 may occasionally aggravate a pre-existing diathesis as the 

 tubercular or scrofulous, or may produce ephemeral dyscratic 

 conditions of health ; but as a rule, after the cessation of 

 the specific exanthem or fever, the bodily organs and func- 

 tions may remain unaffected, so that beyond the passing 



