94 ON THE CONDITIONS FAVOFEING FERMENTATION. 



fectly certain that the latter process can originate de novo — that is, 

 under the influence of certain general or special conditions, and 

 where specific contagia of any kind are at first absent though they 

 subsequently appear as results or concomitant products. So that 

 an exclusive theory of " contagion," as the only present cause of 

 communicable diseases, is not supported by experimental evidence. 



Secondly, that some contagia are mere not-living chemical prin- 

 ciples, though others may be living units. 



Thirdly, that even in the latter case, if the primary contagious 

 action be really due to the living units and not to the media in 

 which they are found, such primary action is probably dependent 

 rather upon the chemical clianges or " contact actions " which they 

 are capable of setting up than upon their mere growth and vege- 

 tative multiplication. 



Fourthly, that where we have to do with a true living contagium 

 (whether pus-corpuscle or ferment-organism), the primary changes 

 which it incites are probably of a nature to engender (either in 

 the fluids or from the tissue-elements of the part) bodies similar to 

 itself, so that the infected part speedily swarms therewith. When 

 pus from a certain focus of inflammation comes into contact with 

 a healthy conjunctiva, and therein excites a contagious form of in- 

 flammation, no one adopts the absurd notion that all the pus-cor- 

 puscles in this second inflammatory focus are the lineal descen- 

 dants of those which acted as the contagium ; and the mode of 

 action may be altogether similar when matter containing "Bacilli, 

 by coming into contact with a wounded surface, gives rise to splenic 

 fever and the appearance of such organisms all through the body. 

 The old notion about the excessive self-mujtiplication of the 

 original contagium is probably altogether erroneous. 



Thus all the distinctive positions of those who advocate a belief 

 in the so-called " Grerm-theory of Disease," or rely upon the ex- 

 clusive doctrine of a " Contagium vivum," seem to be absolutely 

 broken down and refuted. We may give that attention to the ap- 

 pearance and development of independent organisms in associa- 

 tion with morbid processes which the importance of their presence 

 demands, but we must regard them as concomitant products, and 

 not at all, or except to an extremely limited extent, as causes of 

 those local and general diseases with which they are inseparably 

 linked. 



