NON-RECURRENCE OF DISEASES. 129 



quantity of the products of the fermentation. Of course, 

 there has been consumed a great mass of the peculiar fer- 

 mentable substance, on the pre-existence of which, the 

 susceptibility to small-pox was founded. In inoculated 

 cases, as a general rule, the disease is milder, the pustules 

 are much less numerous, and the peculiar matter is con- 

 sumed in much smaller quantity, while the products are 

 consequently less. A vaccination produces, usually, only 

 one small vesicle. Its fermenting power consumes, there- 

 fore, but a minute amount of matter, and produces but 

 little virus. Yet, commonly, by each of these processes, 

 the peculiar fermentable material is totally consumed, and 

 the person is commonly protected from a subsequent at- 

 tack of small-pox. 



This objection to the theory of a ferment, seems un- 

 answerable. But it may be strengthened by adverting to 

 the fact, that by making many insertions of vaccine virus 

 in different parts of the body, we may act on a great deal 

 of the fermentable matter, or, by making but one or a 

 few, we may consume but little. Yet, in either case, no 

 one pretends to say that the degree of protection, or the 

 liability to a re-vaccination is altered. These objections, 

 while they unsettle the hypothetical basis of Liebig's ex- 

 planation, totally destroy its theoretical conclusions. A 

 peculiar matter is assumed as existing, is supposed to be 

 consumed, and not to be usually reproducible. This mat- 

 ter, however, may be equally well consumed by a small or 

 great fermentation, its own quantity seeming to have no 

 relation to the extent or activity of the process, which is 

 governed solely by the mode of using the ferment. How 

 will the analogy, upon which the whole theory rests, sus- 

 tain the argument of the great chemist? There is a cer- 

 tain quantity of gluten to be consumed in pannification, 



