Studies on plant cancers—l, The mechanism of the formation 
of the leafy crown gall* 
MICHAEL LEVINE 
(WITH PLATES I7 AND 18) 
Smith in 1916 (1) announced a new type of crown gall, con- 
sisting of leafy shoots, which was produced by inoculating the 
leaf axils of a plant, where a dormant bud was present, with Bac- 
terium tumefaciens. Similar leafy crown galls were produced by 
inoculating the midvein of the leaf of the tobacco, with the 
bacterial organism. Smith considered this type of crown gall 
identical with the atypical teratoid embryomata found in the 
animal. In 1917 (2) he showed further evidence of the power 
of this organism to produce leafy shoots in fifteen different families 
of plants. He contends that the leafy tumor is produced by inocu- 
lating Bacterium tumefaciens into the tissue of a susceptible 
species in the vicinity of totipotent cells. 
Levin and Levine in 1918 (3) indicated that these leafy shoots 
are always secondary and that the crown gall develops first and 
then a group of crown gall cells become differentiated and give 
rise to a tissue, an organ, or potentially an entire plant, the leafy 
shoot. According to these authors, such differentiation of cells 
of a malignant tumor does not occur in animal cancer. Crown 
gall represents only one type in the large group of pathological 
processes known under the general term ‘‘cancer.”’ 
It occurred to the writer that if, as Smith claims, Bacterium 
tumefaciens inoculated into the epidermis (epithelium) of a plant 
gives rise to an epithelioma and a similar inoculation into the 
cortex or vascular bundles (connective tissue) produces a sarcoma, 
then the inoculation of a plant in any region of totipotent cells (bud 
Anlage), which are known to produce leafy shoots under normal 
conditions should produce them under the added stimulus of Bac- 
terium tumefaciens much more readily and in greater abundance. 
*From the Department of Cancer Research of the Montefiore Hospital, New 
York, Dr. Isaac Levin, Chief. 

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