LEVINE: STUDIES ON PLANT CANCERS—I 451 
young plants in which the growing regions had been inoculated 
four months previously. In one case only has a small leafy shoot 
been formed (Fic. 10, 0). This, however, appeared after the 
crown gall had been well established.' The plants are all dwarfed, 
as may be seen by comparing Fic. 10, a, b, c, e, and f, with d, one 
of the control plants. 
SUMMARY AND CONCLUSIONS 
1. Bacterium tumefaciens inoculated by pricks of a delicate 
needle into the marginal notches of a leaf of Bryophyllum calyci- 
num, where totipotent cells are present, results in the formation of 
a crown gall as readily as in other plants used for inoculation but 
without leafy shoots. 
2. Inoculation of Bacterium bammefaitens into the tissue of a 
leaf of B. calycinum in the vicinity of a small bud causes the forma- 
tion of a gall and interferes with the normal development of the 
bud or leafy shoot. 
3. Inoculation of Bacterium tumefaciens into the midvein 
of a young or old leaf detached from or attached to the mother 
plant results in the development of a large gall without the develop- 
ment of leafy shoots. 
4. Inoculation of Bacterium tumefaciens into the growing 
region of the stem of a young plant causes the development of 
the ordinary crown gall with the occasional and subsequent devel- 
opment of a leafy shoot. 
5. Bacterium tumefaciens does sit cause the formation of 
leafy shoots in Bryophyllum calycinum but rather inhibits and 
retards their normal development, when inoculated into the 
totipotent cells which appear at the notches of the leaf. 
LITERATURE CITED 
. Smith, E. F. Crowngall studies showing changes in plant struc- 
tures due to a changed stimulus. Jour. Agr. Research 6: 179-182. 
pl. 18-23. 1916. 
——  Embryomasin plants. (Produced by bacterial inoculations.) 
The John Hopkins De Bull. 28: 277-294. pl. 26-53. 1917. 
Levin, I., & Levine, M. Malignancy of the crown gall and its 
analogy to Heabre cancer. Proc. Soc. Exp. Biol. and Med. 16: 
21-22. 1918. 
Lael 
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