CHAPTER IX. 
CONCLUSION. 
Tue MicRoBIAN THEORY COMPARED WITH OTHER 
QHEORIES PUT FORWARD TO EXPLAIN THE 
OriciIn or Contagious DISEASES. 
THE parasitic theory of diseases is far from being 
generally adopted by medical men ; at this very time 
the theory is actively opposed by medical practitioners 
of high standing, who are advocates of the theory of 
the innate character of diseases. In their opinion, the 
disease is spontaneously developed in the patient, or, 
at any rate, under the influence of a contagion of 
which the nature is still unknown. They consider that 
it is only a secondary complication when microbes are 
found in the blood, and that these microbes are not 
the cause of the disease, nor even the contagious 
element, nor the vehicle of contagion. In a word, 
the microbian theory is in their eyes a purely gratuitous 
hypothesis. 
Admitting with them that the microbian theory is 
