The _cocco-bacillus_ found by Lignieres in the blood and exudate of the patients has more plausible claims to being the specific germ. This is an ovoid bacterium, somewhat smaller than that of chicken cholera, and like it pigmented at the poles and clear in the central part, a characteristic feature of the group of Pasteurella of Trevisan. This group includes the nonmotile germs of swine plague, the septicæmic pneumo-enteritis of sheep, wildeseuche, and septicæmia of rabbits and chickens, as well as that of fowl cholera; all stain easily in gentian violet and fuchsin, and all cause some form of hemorrhagic septicæmia. The germ is ærobic and grows best in peptonized bouillon to which a little serum has been added. It forms, in peptonized gelatin, round colonies, at first transparent and later opaque or milky, and without liquefaction. The cultures when inoculated subcutaneously proved fatal to Guinea pig, rabbit, rat, mouse, dog, cat, sheep, pig, ox, ass, pigeon and chicken. Intravenous inoculation on the horse of 1 to 2cc. of the culture kills in a few hours, the temperature having risen to 104° F., the mucosæ acquire a dull brown tint, the eyes are swollen and weeping, enteritic colics appear, the limbs may swell and there may be painful arthritis and jaundice. At the necropsy the blood is black and incoagulable, the muscles as if parboiled, the liver a deep violet, the intestinal mucosa congested, a yellowish or reddish effusion in the pericardium and numerous petechiæ on the serosæ. Subcutaneous inoculation causes an enormous inflammatory œdema resulting in a sanguinolent abscess, in case the subject survives. There are also hyperthermia (106° F.), dulness, stupor, weakness, staggering, and congested, swollen, weeping eyes. Intratracheal injection is harmless to the horse. Lignieres finds his cocco-bacillus in the expectoration at the outset and in the nasal and guttural forms of the disease later, but not in the blood nor lungs after death, as it is then replaced by streptococci, the great reproduction of which is favored by its presence. In ordinary cases of equine influenza it is often impossible to find the cocco-bacillus in the lung or other organs after an illness of 8, 10 or 15 days. (Lignieres). Lignieres appears to have omitted the obvious test of the infection of other horses in the same stable, from the cases produced by his experimental cultures, so that we must still call for more confirmatory proof. Cadeac, indeed, assures us that cultures of cocco-bacilli taken from cases of equine influenza, are often innocuous. Deadly as the germ cultures of Lignieres prove, they appear to lack that element of extreme infectiousness shown by equine influenza when the susceptible animals come into proximity with the sick.