ry probable. At any rate, it is important to know
this for certain, for if it be so, then the comma bacilli will not thrive
in a cesspit, and then further disinfection would be unnecessary. These
bacilli thrive best in fluids containing a certain amount of nutriment.
Experiments have not yet shown the limits in this respect, but Koch has
found them capable of growing in meat broth diluted ten times.

Again, if the nutrient medium become acid in reaction their growth is
checked, at least in gelatine and meat infusion; but singularly enough,
they continue to grow on the surface of a boiled potato which has become
acid, showing that all acids are not equally obnoxious to them. But here,
as with other substances which hinder their growth, they do not kill the
bacilli. Davaine has shown that iodine is a strong bactericide. He
experimented with anthrax bacilli in water to which iodine was added, and
the bacilli were destroyed. But practically the organisms have to be dealt
with in the alkaline contents of the bowel, or in the blood or fluids of
the tissues, where iodine cannot remain in the free state. Koch found that
the addition of an aqueous solution of iodine (1 in 4,000) to meat
infusion, in the proportion of 1 in 10, did not in the least interfere
with the growth of the bacilli in that medium. He did not pursue this line
of inquiry, seeing that in practice larger quantities of iodine than that
could not be given. Alcohol first checks the development of the comma
bacilli when it is mixed with the nutrient fluid in the proportion of 1 in
10, a degree of concentration which renders it impracticable for
treatment. Common salt was added to the extent of 2 per cent. without
influencing the growth of the bacilli. Sulphate of iron, in the proportion
of 2 per cent., checks this growth, probably by precipitating albumimites
from the fluids, and possibly also by its acid reaction; certainly it does
not seem to have any specific disinfecting action--i.e., in destroying the
bacilli. Indeed, Koch thinks that the admixture of sulphate of iron with
faecal matter may arrest putrefaction, and really remove what may be the
most destructive process to the comma bacilli. Hence he would distinguish
between substances which merely arrest putrefaction and those which are
bactericidal; for the former may simply serve the purpose of preserving
the infective virus. Among other substances which prevent the growth of
the comma bacilli may be mentione