Abstract
1. Spirochoeta gallinarum can be cultivated in suitable artificial media for many successive generations and probably for indefinite periods. The presence of fresh tissue and a certain amount of oxygen seems to be essential for its growth. No perceptible odor is produced in the cultures. 2. The maximum growth of Spirochoeta gallinarum is reached on about the fifth day, but the phase of degeneration commences slowly and gradually, so that in this respect the gallinarum differs from the duttoni, kochi, obermeieri, or novyi, whose cultures are characterized by sudden onset of degeneration soon after the maximum growth is attained. 3. No rod formation resembling bacilli arises in the course of multiplication of Spirochoeta gallinarum in cultures. Many round or oval bodies appear in old cultures, but no infection of animals or formation of spiral forms from these granules has been produced. The granules are probably the degeneration products derived from the periblast of the spirochoetoe. 4. Cultures of Spirochoeta gallinarum, either old or young, do not contain a form which passes through a Berkefeld filter (V) that infects chickens or grows into spirochaetae. 5. Spirochoeta gallinarum remains virulent for chickens after being in cultures for at least thirteen generations, but it may become avirulent under certain cultural conditions. The inoculation of chickens with the attenuated culture renders the birds refractory to the subsequent infection with a virulent strain. 6. When the spirochaetae are cultivated in the media containing rabbit kidney instead of chicken muscle, the individual specimens are somewhat thicker, but otherwise typical. 7. Spirochoeta gallinarum multiplies in culture by transverse division. No positive evidence of a longitudinal division has been obtained.