158 DISEASE GERMS 



matter, and another tube through which the breath 

 of an animal, dying from the disease, had been 

 passed. I carefully moistened the wool and the tube 

 with perfectly pure glycerine, and subjected the fluid 

 to examination with the ^th. 



Although in each case I have seen particles 

 resembling those already many times referred to, I 

 do not attach much importance to these two 

 isolated observations, or look upon them as con- 

 clusive, for in the first place the number of minute 

 particles of various kinds present makes it impossible 

 to identify with any certainty the supposed particles 

 of contagium ; secondly, as there are undoubted 

 sporules of fungi, I could not prove that the very 

 minute particles which I should be inclined to regard 

 as the contagium had not been developed from these ; 

 and, thirdly, in such an enquiry it would be wrong in 

 principle to place much reliance upon only one or 

 two observations. 



At the same time it is only right to state that the 

 piece of wool in one of the tubes, through which the 

 breath had been passed, exhibited a much greater 

 number of minute particles, resembling those which I 

 regard as particles of contagium, than were obtained 

 from the second piece of wool at the other end of the 

 same tube, by which the air was subjected to a second 

 filtration. It does, therefore, appear possible to de- 

 termine the question from this experimental side. 

 The microscopical part of the investigation presents 



