Address of Professor Hucley. 391 
through and become intermixed, but stopped the eran of 
: r the fer- 
was that the agent thus intercepted must be a solid material. 
In point of fact, Helmholtz’s experiments narrowed the issue, «)_ 
1 See ae 
The researches of Schroeder and Dusch in 1854, and of © 
Schroeder alone, in 1859, cleared up this point by experiments 
which are simply refinements upon those of Redi. A lump of 
cotton-wool is, physically speaking, a pile of many thicknesses 
of a very fine gauze, the fineness of the meshes of which de- 
hen upon the closeness of the compression of the wool. 
ow, Schroeder and Dusch found, that, in the case of all the 
ege), an infusion boiled, and then allowed to come into contact 
with no air but such as had been filtered through cotton-wool, 
neither putrefied nor fermented, nor developed living forms. It 
is hard to imagine what the fine sieve formed by the cotton-wool 
ee: ae 
