48
Scientific Memoirs by
secondary symptoms may make their appearance in an aggravated form. The
difficulty of explaining these phenomena satisfactorily at once disappears if the
possibility of the action of two distinct factors be recognised, the one originating
in the environment and giving rise to the initial symptoms, and the other origin-
ating within the organism and giving rise to the secondary ones.
We have good reason to believe that the primary cause is neither manufac-
tured nor multiplied within the bodies of the sick, but there is every reason to
believe that its action may be capable of leading to the development of toxic
materials there. The action of the primary cause certainly induces profound
changes in the character of the contents of the intestinal tract, and it is impossi-
ble to deny that such changes are well adapted to give rise to corresponding al-
terations in the nature of the schizomycete population there. As we have already
seen, any sudden change in the constitution of an environment containing a mixed
population of schizomycete organisms must almost inevitably give rise to
alterations in the prevalence of particular forms, those which were most adapted
to the environment in its original state being liable to relative repression, and
certain of those which were primarily repressed finding the conditions now favour-
ing their dominancy. This is a proposition which can hardly be questioned even
by those who insist most strongly that the forms of schizomycetes which occur
most abundantly in the contents of the intestinal tract in cases of cholera
ought to be regarded as the essential determinants of the disease. But all the
forms which are present, whether under normal circumstances or in the choleraic
condition, must unequivocally be giving rise to bye-products of the decompositions
which they determine in their environment in connection with their growth and
multiplication, and which are liable to be absorbed in greater or less amount.
Those forms which abound most under normal circumstances must either give
rise to innocuous products or to products which are only absorbed in such small
quantities as to be incapable of causing injurious effects. But it by no means
necessarily follows that those which come to prevail most under the influence
of a profound change in the environment should resemble them in this respect.
We know that many distinct forms may come to the front under the abnormal
choleraic condition of the intestinal contents, and some of these at all events are
certainly capable of manufacturing noxious products, as is clearly demonstrat-
ed by the phenomena following their artificial introduction into the system by
subcutaneous or intraperitoneal injection.
It does not, however, follow that they are all alike in this respect, and
certain experimental data seem at all events to suggest that they differ very
greatly in regard to it.* But if this be so, we clearly have a very satisfactory
*In the early part of the year 1886 I carried out numerous experiments on the effects of intraperitoneal
and subcutaneous inoculation of choleraic-bacilli, and one of the results which was arrived at, and which
appeared to be very inexplicable in the light of the then universally accepted belief that choleraic commas
were necessarily invariably of the same species, was that whilst the materials derived from a particular-
case of cholera usually produced fatal effects, those from other cases were apparently entirely innocuous.