LEVINE: CROWN GALL ON BRYOPHYLLUM 455 
TABLE 2 
UNINOCULATED NOTCHES OF LEAVES OF BRYOPHYLLUM CALYCINUM 
No. of notches No. of sprout- 
No. of leaf per leaf ing buds 
I 17 14 
2 18 9 
3 16 II 
4 15 6 
5 17 10 
6 18 9 
7 17 4 
8 15 6 
9 14 II 
10 15 
Il 16 10 
12 17 
195 106 
It appears from these data that Bacterium tumefaciens does 
not stimulate bud development, even in the presence of condi- 
tions which favor it. B. tumefaciens, it appears, induces a neo- 
plasm which offers mechanical obstruction to the transportation 
of fluids, which, in turn, calls forth bud proliferation, as shown 
in the rubber plant (Levine 1924). If bent stems induce partial 
interference in the conducting system, which is responsible for 
the development of shoots in the notches of leaves of Bryophyl- 
lum calycinum, as held by Loeb (1918 0), it appears to be 
reasonable to suppose that a disturbance induced by a mass of 
invading meristematic tissue may at least have a similar effect 
on these buds one in 8.4 chances. 
LITERATURE CITED 
Braun, E. L. Regeneration of Bryophyllum calycinum. Bot. 
Gaz. 65: 191-193. f. I, 2. 1918. 
de Vries, H. Ueber abnormale Entstehung secondarer Gewebe. 
Jahrb. Wiss. Bot. 22: 35-72. pl. 2, 3. 1891. 
Goebel, K. Einleitung in die experimentelle Morphologie der 
Pflanzen. 142-148. Leipzig, 1908. 
Levine, Michael. Studies on plant cancers—I. The mechanism 
of the formation of the leafy crown gall. Bull. Torrey 
Club 46: 447-452. pl. 17, 18. 1919. 
