PHYSIOLOGY

Pettenkofer on Cholera

NEARLY the whole of the second part of the Zeitschrift fur Biologie, bd. v. (300 pages), is taken up by a long memoir by Prof. Von Pettenkofer on ''Soil and Sock-water in their Relations to Cholera and Typhus" (Boden und Grundwasser in ihren Beziehungen zu Cholera und Typhus) in which he developes at length his views. To many these are probably now well known, but still, it may be perhaps as well to state they are somewhat as follows.

The phenomena of Cholera result from the introduction into the animal system of a cholera poison, which is possibly an organic being, and which we may call z. Now, z is non-reproductive; does not of itself multiply or spread. But there is another distinct thing, the cholera germ (originating in India), which we may call x. x of itself will not produce cholera symptoms. It may remain, and probably may multiply in the human body, and be carried in or on the body from place to place without of itself producing cholera. Cholera symptoms can only be brought about by z, and x can only give rise to cholera, indirectly, by generating z. But x, in order that it may generate z, must come in contact with and act upon another substance, which we may call y. That is, x cannot germinate into z unless it meets with the substratum y; or we may use the idea, thrown out we believe by Dr. Farr, and imagine x and y to be the male and female parents of the offspring z, which is either sterile, or can only reproduce x.

Thus, then, x originating at certain times in India, and meeting with y at once gives rise to z, and an outbreak of cholera is the result. The quantity of z is probably more than sufficient to account for all the cases that occur; the surplus may even perhaps be carried about, and so spread the epidemic; but there being no reproduction of z, the stock would soon be exhausted. With z, however, a quantity of x is also carried about, more particularly by the excrement; x, in fact, clings to its products just as yeast cells cling to a fermented liquid. And whenever x meets with fresh y, it generates fresh z; and so the epidemic travels on, x making itself felt by z whenever it falls upon a store of y. For the existence of y, certain things are necessary, to wit:

1. A soil which, like alluvium, is permeable to air and water for several feet deep.

2. The rise and fall of sock-water. A soil which is permanently dry, or one which is always filled with sock-water, are equally unfavourable for the development of v. The change of level of water is absolutely necessary.

3. The presence of organic and mineral matters on which the variations in the amount of sock-water may act, and out of them produce y.

4. A temperature suitable for such processes of organic evolution.

All these points and many others are fully discussed in a series of chapters with such headings as ''Porous and Compact Soils" ; ''The Soil and the Immunity of Wirzburg"; ''Influence of drinking Water on Cholera epidemics"; ''Considerations on the Cholera epidemic of 1866 in East London, in reference to Soil and Sock-water conditions"; ''Apparent evidences against the 'Soil and Water theory' and for the theory of 'Contact and Idiosyncrasy,''' &c. &c. It concludes with a series of aphorisms, ''On the Origin and Spread of Cholera"; ''On the Influence of Variations in Sock-level on the Enteric Fever of Munich''; and, ''On the Causes of the Immunity of Lyons."