298 A Pathogi the Hog. [April, 



comparatively slight effect, that is, are productive of a mild and 

 not fatal form of the disease, or cause only a scarcely observable 

 reaction. All this cannot find an explanation, if the infectious 

 principle consists in a chemical virus, but is fully explained, if 

 Schizophytes constitute the cause and the infectious principle of 

 the disease, for it is a well known fact that these minute bodies, 

 by passing through a certain cycle of changes or metamorphoses, 

 and propagating to a certain extent exhaust in that medium, in 

 which they are existing, the conditions necessary to their further 

 development and propagation. They then render their medium 

 sterile, and do not undergo any further changes, and do not 

 multiply, unless, and until they are transferred to a fresh and 

 otherwise suitable medium, when again they begin another cycle 

 of metamorphosis and propagation, and multiply with great 

 rapidity. In an animal, which has recovered from an attack of 

 Swine-plague, some of the conditions necessary to the further 

 metamorphosis and propagation of the Schizophytes, it seems, 

 have become either partially or fully exhausted, and are not very 

 soon restored, hence the partial, or as the case may be, perfect 

 immunity. Still, as will be mentioned again, such an animal is 

 usually able, at least within two months after its recovery, to 

 transmit the disease, from which the same itself is not any more 

 suffering, to other healthy animals, though in most cases only in 

 a mild form. 



4. It is a well known fact, and has been observed every- 

 where, not only by myself, but by nearly every one who has 

 any experience in regard to swine-plague, that healthy hogs, 

 which have access to a creek or a small stream of running water, 

 which is further above accessible to, and defiled by, diseased 

 hogs, or polluted with morbid products of swine-plague, or the 

 carcasses of dead hogs, will almost invariably contract the dis- 

 ease; a fact which plainly shows to every thinking man that the 

 infectious principle must be something corporeal, endowed with 

 life, and able, like the swine-plague Schizophytes, not only to 

 withstand the influence of water, but also to live and to multiply 

 in the same. A chemically acting, and invisible fluid, or volatile 

 virus, one should suppose, would become diluted by the water of 

 a creek, small river, or running stream to such an extent as to be 

 perfectly harmless and unable to communicate the disease, be- 

 cause there is no known chemical of an organic nature, but what 



