This is a bacillus somewhat similar in size to the bacillus anthracis, and it is also identical with Pasteur's " vibrions septiques" which he found in his "septicaemie." (See Fig. 146).

Malignant oedema has been observed in man after infection of severe wounds, compound fractures, etc., by the bacillus. There is a cutaneous emphysema, decomposition, and oedematous swelling of the superficial muscles, and death generally results in a few days. The author met with bacilli closely resembling this form in a case of cancrum oris. The bacillus is a slender rod, somewhat thinner than the anthrax bacillus and with rounded ends. It tends to grow into long threads even in the body, and it is slightly motile by means of cilia. The bacilli are strictly anaerobic, so that they can only be cultivated by taking precautions to exclude the oxygen of the air, as in an atmosphere of hydrogen, or by a stab-culture deeply into a solid culture-medium. In growing the bacillus evolves gas and produces a putrid odour. It is decolorized by Gram's method. It bears spores in the middle of the rods. The source of the bacilli in experimental observations is various kinds of decomposing matters, dust, garden earth, etc., and they are evidently widely dispersed.

The bacilli produce disease when inoculated in mice, guinea-pigs, rabbits, etc., and this occurs whether their source be such external matters as garden earth, or pure cultivations. Death usually residts in twenty-four to forty-eight hours. Around the point of inoculation the subcutaneous tissue and superficial muscles are infiltrated with a dirty red stinking fluid in which are bubbles of gas. The bacilli are found in the oedematous fluid; none are visible in the blood. The bacilli, in fact, remain in the subcutaneous tissue, and on the surface of organs, not penetrating into the parenchyma and not extending tto the bloodvessels. It is to be added that they grow vigorously after death, penetrating into the substance of organs and into the vessels. In the mouse the bacilli penetrate more markedly during life into tissues and blood-vessels, and the appearances approach to those of anthrax.

Fig. 146. - Bacillus of malignant oedema, x about 1000.