Streptococcus Erysipelatis, the micrococcus of erysipelas, is composed of perfectly globular cells of small size, which have a peculiar tendency to grow into long chains. It has been cultivated on various media, growing slowly at the ordinary temperature, and more quickly when the temperature approaches that of the body. The cocci grow most abundantly in bouillon, and not at all on potato. In growing they form little white spots which "have a characteristic appearance, and do not liquefy gelatine.

In cases of erysipelas they are found in the lymphatic spaces and vessels, which they frequently fill out so as to form a kind of injection of them. They do not extend beyond these vessels, but their poisonous products not only produce intense local inflammation, but, passing to the blood, cause fever and other general symptoms. The bacteria are scarcely at all present in the inflamed area, but are abundant at the margins. The cocci evidently produce their toxine, and subsequently perish, leaving the poison behind.

Erysipelas is producible artificially by inoculation of cultures of this streptococcus. The roost convenient experiment is to inoculate the ear of a rabbit; this leads to an acute inflammation, which terminates in from six to ten days without suppuration. Mice are immune to this microbe. Fehleisen has successfully practised inoculations in man with a view to the treatment of tumours.

In ordinary cases of erysipelas the bacteria are usually derived from the air, but may be conveyed by contact.' The point of entrance is probably in all cases a wound, but it may be a very trivial one.