i 9 9 



influence much sooner than others, there are others who are 

 insusceptible to the vaccine virus altogether. So much for 

 the exanthemata. 



Of those acute infectious diseases which are not due to 

 specific animal poisons I may instance erysipelas and diph- 

 theria, to both of which, whilst most persons are subject to 

 their influence, some are peculiarly susceptible, and the 

 susceptibility is such that it persists throughout life, and is 

 unquestionably hereditary. " In both," as Mr. Hutchinson 

 says, " that with which we have to deal is a personal and 

 inherited peculiarity, giving proclivity when certain exciting 

 causes are brought to bear, to peculiar forms of inflammatory 

 action." There can be no doubt that the difference between 

 the states of health produced by the specific poisons, and 

 those which are due to inflammation from non-specific causes, 

 are strongly and well marked, the latter coming under the 

 law of intensification by habit. The same authority says : 

 In the development of such inflammations as those of ery- 

 sipelas, diphtheria, elephantiasis, and especially when not due 

 to contagion, the constitution of the individual takes a large 

 share, and the mere fact of their occurrence reveals his 

 previous proclivity. The disease originates in part from 

 without, but in part also from within. It is not an instance 

 of intrusion, but of development, and the peculiarities of 

 blood, tissue, or nervous system, are exactly those which are 

 capable of increase. 



It is, indeed, beyond question that amongst the causes of 

 erysipelas and diphtheria, family and individual susceptibility 

 must be regarded as factors of prime importance. It would 

 be easy to cite cases in defence of this assertion, but as the 

 fact is too well known to be denied, I shall content myself 

 by the mere statement of it. 



