Crown-Gall of Alfalfa

1. The resting spores, placed in water cultures, develop into sporanges. 2. Within these sporanges are formed motile zoospores of two sizes; frequently one large zoospore and many small ones are formed in the same sporange. 3. One or several small zoospores may become attached to one large zoospore. Only one remains permanently attached. There is some evidence that this attachment is related to a sexual fusion. 4. The movement of the large zoospore continues after the attachment of the small one. 5. The small zoospores, the large zoospores, and the united zoospores (zygotes?) become amoeboid after a period of motility. 6. In the amoeboid state, singly or in groups, these bodies may be observed upon the surface of the host. 7. In infected soil young alfalfa seedlings develop galls in which plasmodia are found. 8. In older galls similar plasmodia are found, which ramify through the tissues of the gall. 9. The resting spores are formed in cavities within the tissues of the galls. 10. The cytoplasmic and nuclear contents of the resting spores in the dormant condition correspond to those of the plasmodium in the stage immediately preceding the formation of resting spores.