On peptonized gelatin at 98° F., and less rapidly at ordinary temperature, it grew as white, opaque, colonies which gradually extended and united in many cases. The gelatin was not liquefied. In peptonized bouillon it produces turbidity for one or two days, after which the microbe precipitates leaving the liquid clear. The reaction is unchanged. It lost virulence rapidly when kept in artificial culture or at a temperature of 122° F., and was killed by a temperature of 150° F. Yet it survived drying at moderate temperatures. Cadeac found that the dried expectoration or blood, diffused in the inspired air produced pneumonia with certainty in solipeds. Schütz and Fiedaler injected pure cultures into the lung, and in other cases into the trachea, thereby inducing pneumonia. Twenty grammes of the culture injected into the trachea raised the temperature 2° or 3°, but this lessened on repetition and after four or five treatments the subject proved immune. Lignieres (1897) discovered his _cocco-bacillus_ in the exudation in the tissues in the early stages of contagious pneumonia, from which it disappears, giving place to other bacteria, and usually streptococcus, as the disease reaches its maximum. (See Equine Influenza for description). His theory is that the cocco-bacillus, which is slightly smaller than the bacillus of chicken cholera, and appears like a diplococcus when stained, and which may not be found after the first eight days of infectious pneumonia, is the starting point of disease, in this and influenza, making the system very receptive of the streptococcus of strangles and of other bacteria, the identity of which determines the nature of the malady. The diplococcus or streptococcus of Schütz in his opinion is none other than the strangles streptococcus which finding a congenial home in the animal invaded by his cocco-bacillus, pervades the system and determines the pathological phenomena of contagious pneumonia. There are certain obstacles to the unreserved acceptance of Lignieres’ conclusions, among the chief of which is the absence of evidence that horses, successfully inoculated with his cocco-bacillus in pure cultures, can infect others standing near them with the same rapidity and certainty, as does the casual case of influenza, or even of contagious pneumonia. The same holds true of the supposed identity of the streptococcus and that of strangles. Abscesses containing streptococci, were formed in the seats of inoculation with Schütz’s organism, but there is no evidence that the horses suffering from such abscess affected susceptible horses standing beside them, as do ordinary cases of strangles. The cocco-bacillus may be a concurrent cause of contagious pneumonia, but we need more proof to show that it is the essential cause, even as we need proof of the absolute identity of the streptococcus of strangles and brustseuche.