THE PRINCIPLES OF BOTANY. 293 
being detected and mended, no trace of the same class of dis- 
ease has since manifested itself. 
Nothing, then, appears to us to be more clearly established 
than that certain effects follow the use of water in which 
fungal matter is found, but whether these effects are the result 
of certain chemical changes, fungal or other poison, is not so 
clear ; but it is important to know that we are able to detect 
the source of the mischief, and that when we have removed 
or prevented the access of the matter by which the fungi are 
produced such mischief speedily ceases. 
In an agricultural point of view, the substances which do 
so much mischief in being allowed to fester beneath our 
towns and to contaminate the wells assume an importance 
which cannot be well over-estimated. Sewage waters, so 
mischievous if not got rid of, are now found to contain fertil- 
ising matters of great importance. Croydon and other large 
towns are at present utilising sewage matters, and on a visit to 
the former place we were pleased to see that while the sewage 
of the town, where it first enters upon the soil, is highly 
charged with the sewage fungus ; the sticks and grasses in 
the carriers are covered with whole masses of this substance, 
but after percolating through the soil the exit from the car- 
riers will be found to contain water all but pure, in which 
fishes and the usual plants of pure streams will be found to 
do well — a circumstance never to be observed until the soil 
had absorbed the chemical substances by which the fungus is 
produced. The result is, besides purification, the production 
of enormous crops, especially of grass and roots, and this 
without any additional manure whatever, and with the result 
that the value of the land has increased a hundredfold. 
Thus it is that effete animal matters are converted into 
wholesome vegetation, and by this means, while the food of 
the people is increased, many virulent diseases are checked ; 
and, as shown by statistical returns, when this or any other 
efficient means of carrying off sewage is adopted, the death- 
rate is very considerably diminished. We are yet far from 
knowing the natural history of the fungoid substance re- 
ferred to ; its real relationship, or whether there be few or 
many species, has not been determined, but sufficient is known 
to enable us to conclude that these almost invisible agencies 
exert a most decided influence on the animal economy. But 
further, there is reason to think that the sporules of fungi 
floating in the air are a constant source of mischief, as stated 
by that learned fungolist, the Rev. M. J. Berkeley: 
“ Fungi were long regarded as the mere creatures of pu- 
trescence, and therefore as the consequence, not the cause, of 
