244 D. D. CUNNINGHAM. 
the reproductive elements of Oidium /actis, just as that of the 
cow normally contains those of Pi/obolus erystallinus and other 
stercoreous fungi. 
The development of the Oidium is, as we have seen, coinci- 
dent with a great increase in the acidity of the basis, and the 
question naturally suggests itself, how far the two phenomena 
are causally connected, and how far the increased acidity is due 
to a fermentive action dependent on the growth of the fungal 
elements. That it is partially—but only partially—dependent 
on this appears to be clear from the’ result of a series of experi- 
ments in which neither Oidium nor any other mould-fungus was 
developed, and in which, at the same time, a distinct but tem- 
porary increase in acidity sometimes manifested itself. The 
notes recorded regarding one of these cases are as follows :—A 
portion of fresh acid alvine excretion was boiled and set in a moist 
chamber. Twenty-four hours later there was a distinct increase in 
the degree of acidity. On the following day it exhibited a mixed 
reaction, being faintly and transiently acid when first applied to 
the test paper, and the acidity passing off and being replaced 
by permanent alkalinity on drying. On the next day all trace 
of acidity had disappeared, and a permanent and distinctly 
alkaline condition was present. In other cases, however, and 
these constituted a great majority, the reaction at the close of 
twenty-four hours either remained unaltered, or indicated an 
increase in alkalinity, and after forty-eight hours’ reservation an 
alkaline condition was almost invariably strongly pronounced. 
The increase in acidity never approached in degree that asso- 
ciated with the development of Oidium, and the phenomenon, 
where present, may, I believe, be regarded rather as an evidence 
of diminished manufacture of alkaline products than of any 
positive increase in acid-formation. The reasons for this belief 
are the following :—The appearance of alkalinity in the materials, 
whether boiled or unboiled, is associated with an enormous 
development of bacterial elements. During the stage of acidity 
normally coinciding with the development of Oidium, bacterial 
development seems to be suppressed or very greatly retarded, 
and it is only when the fungal development ceases that it comes 
actively into play. Prolonged boiling also causes an immediate 
suppression of bacterial development for the time, and at the 
same time permanently suppresses the oidial elements. If, then, 
any volatile acid or alkaline elements are originally present, a 
development of either acid or alkali may seem to occur, due really 
to alterations in the relative proportions of the products incident 
on the escape of volatile compounds and not on any increased 
formation. 
As noted above, while the suppression of fungal elements by 
