_Virulent Products._ Infection is present sooner or later in all the morbid animal products. The nasal mucus, bronchial exudate, saliva, tears, contents of the cutaneous vesicle, milk, contents of the bowels, and the blood have been successfully inoculated on susceptible subjects. Inoculations with blood failed with Bryce, but proved successful with Konnhauser, Krajewski, Even, Lignieres and Physalix, so that the first named cases may be explained by a prior immunity, or by a too advanced stage of the case which furnished the matter. The virulence is not lost nor even diminished by drying at ordinary temperatures, freezing (10° F.), nor by moderate dilution in water. Prolonged exposure at ordinary temperature, however, reduces the virulence, which is greatly impaired in 15 to 25 days (Laosson), or, if dried, in three months and upward (Krajewski). Virulence is easily destroyed by disinfectants,—thorough washing (Menard) hypochlorous acid (Trasbot), chloride of lime, mercuric chloride, etc. _Forms of Distemper._ This disease is extremely protean in its manifestations. Many cases, in country districts especially, are manifested by a slight fever, with a _catarrhal condition of the mucosæ_ of the nose, eyes, and throat. In other cases there may be simply a slight _conjunctivitis or keratitis_, and in still others a _cutaneous eruption_, papular, vesicular or pastular. In some instances there is slight _gastric_ or _hepatic disorder_ with inappetence nausea, and vomiting or some irregularity of the bowels. In such cases recovery may take place in eight or ten days. In the more severe forms, especially seen in house and city dogs, and in high bred and confined dogs generally, the fever is high and persistent and the disorders often predominate in particular organs, hence we see a _catarrhal form_, a _conjunctival_, a _bronchitic_, a _pulmonary_, a _gastro-intestinal and hepatic_, a _cutaneous_ and a _nervous_. The severe cases may last for twenty or thirty days or even in their sequelæ for several months. Exposure to cold contributes greatly to a pulmonary attack even in inoculated cases (Lignieres). The _mortality_ varies greatly. In country dogs it may be below 20 per cent., whereas in city dogs and those kept confined in close quarters and in large numbers it may rise to 50, 60 or even 70 per cent. _Prognosis_ is especially unfavorable in severe cases; in those profoundly affecting the brain, lungs or liver; in high bred or pampered dogs; in the very young; in the debilitated, anæmic or rhachitic; in those that have been recently imported from another climate and are as yet unacclimated. Puppies from debilitated dams, or those raised in a large litter with insufficient nourishment, or older dogs confined to a purely vegetable diet show less power of recuperation. Profound prostration and offensive odor, from excess of toxins are always to be dreaded.