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CONTAGIOUS PARTICLES 



It may be carried a considerable distance from its 

 source without losing its marvellous power of causing 

 in the organism invaded a series of changes resembling, 

 and often in very minute particulars, the phenomena 

 which have occurred in the organism from which it 

 was derived. 



And it is established that there exist different 

 kinds of contagious living bioplasm, each capable of 

 occasioning specific phenomena which distinguish it. 

 The poison of small-pox will produce small-pox, not 

 typhus fever, or measles, &a, nor will any of these 

 produce small-pox. 



Without therefore pretending to identify the actual 

 particles of the living bioplasm of every contagious 

 disease, or to be able to distinguish it positively from 

 other forms of bioplasm, healthy and morbid, present 

 in the fluids, on the different free surfaces, and in the 

 tissues in such vast numbers, I think the facts and 

 arguments I have advanced prove first, that the con- 

 tagious virus is living and growing matter ; secondly, 

 that the particles are not directly descended from any 

 form of germinal matter or bioplasm of the organism 

 of the infected animal, but that they have resulted 

 from the multiplication of particles introduced from 

 without ; thirdly, that it is capable of growing and 

 multiplying in the blood ; fourthly, that the particles 

 are so minute that they readily pass through the walls 

 of the capillaries, and multiply freely in the inter- 

 stices between the tissue elements or epithelial cells ; 



