GENERAL MORPHOLOGY AND PHYSIOLOGY.. 145 



That many organisms are causally related to 

 disease, there is strong evidence in proof; for no 

 organism can be considered to be productive of 

 disease unless it fulfils the conditions which have 

 been laid down by Koch (p. 2). Great stress must 

 be laid upon the importance of successive cultiva- 

 tion through many generations, as the objection 

 that a chemical virus may be carried over from the 

 original source is thus overcome. Any hypo- 

 thetical chemical poison carried over from one 

 tube to another, would, after a great number of 

 such cultivations, be diluted to such an immense 

 extent as to be inappreciable and absolutely 

 inert. 



Though we may accept as a fact the existence 

 of pathogenic organisms, we are not yet in a posi- 

 tion to assert the means by which they produce 

 their deleterious or fatal effects. Many theories 

 have been propounded. It has been suggested 

 that the organisms, micrococci for example, may be 

 compared to an invading army. The tissue cells 

 arrayed against them endeavour to assimilate 

 and destroy them, but perish themselves in the 

 attempt. This might explain the breaking down of 

 tissue, and the formation of local lesions, but does 

 not assist us in understanding the fatal result in 

 thirty-six to forty -eight hours produced by the 

 inoculation of the bacilli of anthrax. Another view 

 is that the invading army seize upon the commis- 

 sariat, appropriating the general pabulum, which 



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