Dr. Von Pettenkofer proceeded to experiment on himself, choosing Munich, in daily communion with Hamburg (where the epidemic was raging), as the place of operations, and sent to Hamburg for the cholera germs. On October 7 he swallowed a centimetre of fresh cholera culture, in the presence of witnesses--_i.e._, infinitely more than could be taken in by touching the lips with contaminated fingers, a cubic centimetre of culture being calculated as containing a thousand million microbes. He in no way changed his manner of living, eating accustomed food, including fruit, cucumbers, and other forbidden articles of diet. During the following week his physiological condition, pulse, temperature, etc., were carefully noted. Nothing unusual occurred but a little internal rumbling and slight diarrhœa, which passed away of itself. Two skilled bacteriologists, MM. Peiffer and Emerich, carefully examined the secretions during this experiment. M. Von Pettenkofer himself thus states the results: ‘The comma bacilli not only prospered in my digestive tube, but had so multiplied in it that it was evident they found a congenial soil. They were found there in quantities, and in a state of pure culture. But on October 14 all the secretions were normal, only containing a few isolated microbes, which had entirely disappeared on the 18th. ‘Now, most bacteriologists assert that the cholera bacilli remaining in the intestines secrete there a poison, which, being absorbed, produces the cholera. But what a quantity of poison must have been secreted by these milliards of bacilli during the eight days’ sojourn in my intestines! Yet I felt perfectly well, had an excellent appetite, felt neither indigestion nor fever, etc., and I attended every day to my usual occupations. Whence I conclude that the comma bacillus, though it may cause a little diarrhœa, produces neither European nor Asiatic cholera. ‘Now, it must not be imagined that I am the adversary of the cholera bacillus; but it is erroneous to suppose that when a specific microbe has been discovered in the secretions of an infectious disease that the means of fighting it has also been discovered. The discovery of the bacillus of consumption was just as interesting as the discovery of the cholera bacillus, but since its discovery phthisis has destroyed neither one man less nor one man more. ‘These (bacteriological) methods for protection against cholera rest purely upon theory, and it seems to be thought that henceforth cholera, etc., ought to behave according to the prevalent theory, instead of theory being modified according to the cholera. Instead of trying to catch the comma bacillus and draw a cordon around it, the essential thing is to make all the dwelling-places of man healthy.’ Such is the vigorous and genuinely scientific experiment of a distinguished medical investigator.