38 THE GERM THEORY OF DISEASE. 



LOGICAL SEQUENCE. 



We may now turn our attention especially to the germ 

 theory of disease; and in doing so, it will be necessary to go 

 back to the discoveries of Schwan and Latour. It was shown 

 that after the discovery that vinous fermentation was depend- 

 ent upon the yeast plant, it was at once assumed that all other 

 fermentations, decompositions, miasms and contagions were 

 also dependent upon the life force. 



This assumption was a logical sequence to the then existing 

 ideas, for it had long been held by the wisdom of the world 

 that all these processes, including contagions and miasms, were 

 of the same order, of the same genus, and were brought about 

 by forces of the same nature. But when this assumption was 

 put forth under the new phase of the matter resulting from 

 the discoveries of Schwan and Latour, it was vehemently 

 denied by a host of scientific men, even among many who 

 accepted the yeast plant as the true explanation of vinous fer- 

 mentation. 



DIFFICULTIES. 



This, as we have seen, rendered it necessary that the facts 

 of each process heretofore regarded as fermentation should be 

 proven upon its own merits. 



The work was at once begun, and the more ordinary fer- 

 mentative processes were developed with considerable rapidity, 

 and have finally been completely worked out and definitely 

 settled, as has been shown. 



The proof, however, that the ordinary decompositions, con- 

 tagious and miasms belonged to the same class and were 

 brought about in the same manner, was maintained with but 

 slight success. 



The organisms found in these were of a different order and 

 the most of them more minute, and for a long time it was im- 

 possible to classify them. Manufacturers of microscopes were 



