THE PRINCIPLES OF BOTANY. 
291 
wliat prevalent, it is not to be wondered at that the medical 
men attributed much of the illness to the water, especially 
when it is known that the substratum of forest marble clays 
is covered up with a porous gravel. The water wells, then, 
are dug in the clay, and the so-called dry wells” are sunk 
in the gravel, and hence, then, all the matter that finds its 
way into the dry wells is percolated into the water wells ; 
and this is doubtless the source of impure water, not only in 
this, but in many similar cases. It hence follows that, as 
originally towns and villages were usually planted on 
streams because the water was good and abundant — but this 
is ruined by drains to the rivers — so, little advance soon 
showed that here and there water could be obtained by sink- 
ing wells, and Cirencester, the ancient Corinium, still pos- 
sesses several wells made by the Romans ; but, alas ! long 
percolation has vitiated this once pure source of water 
supply. 
Now, not only here, but everywhere, a still advancing 
civilisation demands that water be brought from a distance; 
and we hope at no distant date to find all our towns and most 
of our villages obtaining their water from pure but more or 
less distant streams — streams free from the contamination of 
population. 
At present much objectionable matter is taken from Ciren- 
cester by a general system of sewerage, and we refer to this 
in order to point to the significance of the following facts. 
On examining the exit of the sewage water at Cirencester, 
and subsequently at Croydon, we observed that sticks and 
projecting materials in the stream were more or less charged 
with a flocculent gelatinous matter. This matter, under the 
microscope proved to be the same fungus as that found in 
the wells; and the exits of drains into the Thames and 
Severn, in the neighbourhood of towns, will be found to be 
more or less charged with the like fungus. It hence follows 
that if water containing these be deleterious in the one case it 
will be in others, and if it be really true that such water does 
produce disease — even if periodically only — we have, in a 
microscopic examination, a ready means of detecting the 
source of the mischief. 
That it does so we may gather, not only from the cases 
already mentioned, but from one of a more recent date, which 
we at once proceed to detail. 
As poor-law guardian and visitor to the workhouse of the 
Sherborne Union, we were called upon by a note in the 
house-surgeon's book to examine the state of the well and the 
drainage of the premises. In the first place, some defective 
