Crown gall as an anatomical and cytological problem: a review.

Crown gall is a plant disease that affects Gym nosperms and Dicotyledons and produces more or less anaplastic tumors in most parts of the host plant. The causative organism, Agrobacterium fume fade,n.@ (Smith & Town) Conn., induces the out growths by acting on host cells conditioned by wounding. Once the cells have been transformed, the inciting agent becomes unnecessary. Hence forth the tumor shows an unlimited capacity for growth, which is largely independent of any mor phogenetic restraints exerted by the host plant. Crown gall shares its major characteristics with neoplastic growth in general, as encountered both in animals and plants; and much of the crown gall research has been more or less directly inspired by its neoplastic qualities. As a living system, crown gall presents a multi tude of problems. Much of the pertinent informa tion in the field has been acquired by physiological and biochemical studies. Anatomical and cytologi cal investigations have been pursued to a much lesser degree, although these might have been ex pected to complement the picture obtained by other methods. Not even the classical methods of anatomy and cytology have been fully exploited, much less such modern technics as histochemistry and electron microscopy. It is hoped that a review of the existing information on crown gall anatomy