ous membrane, with delicate rosy-red
injection, and some prominence of the solitary follicles and Peyer's
patches. In such cases the intestinal contents were colorless, but
resembling meal-soup rather than rice-water. In only a solitary instance
were the contents watery and mucoid. Microscopical examination of the
intestine and its contents revealed, especially in the cases where the
margins of Peyer's patches were reddened, a considerable invasion of
bacteria, occurring partly within the tubular glands, partly between the
epithelium and basement membrane, and in some parts deeper still. Then he
found cases in which, besides bacteria of one definite and constant form,
there were others also accumulated within and around the tubular glands,
of various size, some short and thick, others very fine; and be soon
concluded that he had to do here with a primary invasion of pathogenic
bacilli, which, as it were, prepared the tissues for the entrance of the
non-pathogenic forms, just as he had observed, in the necrotic,
diphtheritic changes in the intestinal mucosa and in typhoid ulcers.

Passing to speak of the microscopical character of the contents of the
bowel, Dr. Koch said that owing to the sanguinolent and putrescent
character of these in the cases first examined, no conclusion was arrived
at for some time. Thus he found multitudes of bacteria of various kinds,
rendering it impossible to distinguish any special forms, and it was not
until he had examined two acute and uncomplicated cases, before haemorrhage
had occurred, and where the evacuation had not decomposed, that he found
more abundantly the kind of organism which had been seen so richly in the
intestinal mucosa. He then proceeded to describe the characters of this
bacterium. It is smaller than the tubercle bacillus, being only about half
or at most two-thirds the size of the latter, but much more plump,
thicker, and slightly curved. As a rule, the curve is no more than that of
a comma (,) but sometimes it assumes a semicircular shape, and he has seen
it forming a double curve like an S, these two variations from the normal
being suggestive of the junction of two individual bacilli. In cultures
there always appears a remarkably free development of comma shaped
bacilli. These bacilli often grow out to form long threads, not in the
manner of anthrax bacilli, nor with a simple undulating form, but assuming
the shape of delicate long spirals, a corkscrew shape, reminding