FUNGI 329 
mation has of late years been acquired regarding 
the habits and modes of propagation of these 
diseases ; but little as yet has been ascertained 
regarding their essential nature. The pestilence 
still ‘ walks in darkness,’ and neither chemistry nor 
any other science can tell us what is its essential 
nature, nor in what its terrible potency consists. 
If the spores of fungi be really the exciting cause, 
in predisposing circumstances, of zymotic diseases, 
these minute bodies, conveyed through the air, and 
introduced into the body in respiration, could easily 
be detected. Professor Fries has compared the 
relative magnitude of a large proportion of fungoid 
sporules to that of the globules of chyle and blood 
in the human subject, although many are about 
two-thirds of the size of the former and one-third 
that of the latter; while particles of inorganic 
matter can be distinguished by the microscope so 
minute as the 200,000th part of aninch. Be the 
origin of these diseases, however, what it may, it is 
a matter of fact that when cholera appeared in 
this country, in 1847, an extraordinary quantity of 
these microscopic spores were found in the air. 
If they were poisonous, as many of the fungi are, 
or were capable, in the manner of a ferment, of 
exciting morbid actions in the system, it admits of 
being suggested at least that those living in places 
where dense clouds of them were present, being 
