The purging which accompanies the disease may possibly quite clear the bowel of one recovering from it of the bacilli, but after recovery such a one would be as likely as any other again to swallow infected material, when purging would not again occur; at least it has not been found that persons recovered from cholera, and immune to it, are liable to diarrhoea during an epidemic, and that their discharges are infective. If then an immune person swallowed infected material, and if the contents of his bowel afforded all-sufficing nutriment, in which the bacilli were able to multiply to an unlimited extent, his bowiel would become the home of a colony of bacilli, which, owing to the constant renewal of their food supply, and the removal of their waste products, would multiply perpetually, and would perpetually infect his alvine discharges, to the danger of the community; unless indeed, which seems improbable, when we consider the enormous rate at which the bacilli multiply, the churning movements of the intestine so certainly brought all the bacilli within reach of the phagocytes, now invulnerable to them, in the wall of the bowel, that the latter were able to seize and destroy them. But we know that no person who has recovered from cholera ever becomes a source of perpetual danger to the community, and we must conclude therefore that, even if the bacilli are capable of multiplying to a limited extent in the non-living contents of the bowel, that, unlike some harmless species of microorganisms that normally inhabit it, they are not capable of multiplying to an unlimited extent there, but must periodically pass a time and find their nutriment in the living tissues of susceptible individuals.
The truth, therefore, appears to be, that the microbes of cholera find their nutriment in the living tissues of the host, but when the conditions of existence become unfavourable there—i.e. when the phagocytes react to
