typhoid fever and no other disease the world over, and under all conditions. The question comes up—and the pythogenic (putrefaction) theory must be competent to afford an answer, or it will have to be abandoned—In what way can an infection, which must be composed of many heterogeneous and opposing elements, and produced under widely different conditions, be capable of producing in different individuals, each affording a nidus for the development of the poison under an almost infinite diversity of circumstances, one uniform train of symptoms, one specific, well-marked disease? The answer to this is, that it depends on the kind of matter decomposed. To human excrement, above all others, has been given this fatal power. To this recently sewer-gas, which we have already excluded from the chain of possible causes, has been added. But typhoid fever has never been produced by experiments with decomposing substances, nor by products of decomposition accidentally introduced into the human body; and, further, it is opposed to our daily experience. There are vast numbers of houses in which the affluvia of vaults may be detected in all the rooms, others in which the inmates are constantly inhaling sewer-gas, and the fixed as well as the transient inhabitants escape the disease. It is safe to say that cities with defective sewerage are the rule; that some cities and villages are more filthy than others; that in some quarters of a city the decomposition of organic and excrementitious matter is constantly going on; and yet we find typhoid fever prevailing independently of all these theoretical sources of infection: we find it localized in one section, even in one block of buildings, while others presenting equally favorable conditions have not produced a case within the memory of man.
The theory has been seriously damaged by its friends. Not only typhoid fever, but a series of specific diseases, of the origin of which we are in a measure ignorant, have been referred to the decomposition of organic substances. Dysentery, yellow fever, cholera, typhus fever, and the plague have been assigned to this cause. Liebermeister says that this "very circumstance shows that to explain the origin of typhoid fever by a general and indefinite assumption of a decomposition of organic substances is not satisfactory. It is not every kind of decomposition that can produce typhoid fever; it must be some specific form of decomposition which elaborates as a specific product the poison of that disease."
In the epidemic which we are studying we have excluded the theory of contagiousness. We saw in the conditions reasons for excluding the sewers as a means of extension; and I trust, from what I have said of the nature of the disease-germs, the reader is willing to admit that I have some reason for the belief that we can not find an origin de novo in the house-vaults.
The atmosphere in this epidemic is not a probable means of the extension of the germs. We are not able to say positively that the
