LEVINE: CROWN GALL ON BRYOPHYLLUM 451 
developed after inoculation. It has seemed to me to be de- 
sirable to determine the effects of inoculation of the notches of 
these leaves undetached from’ the mother plant and to deter- 
mine the frequency of the leafy crown galls thus formed, as 
compared to the number of the common globular types that 
appear. I have found in my cultures what appear to be mature 
and healthy Bryephyllum plants which developed leafy shoots 
at their notches. The number of shoots formed on these leaves 
resulting from an apparently unknown condition was compared 
with the number of leafy shoots resulting after the inoculation 
with Bacterium tumefaciens. Both plants were grown under 
similar conditions. Up to the present the differentiated globular 
crown gall with leaflets on its surface has not been observed at 
the margin of Bryophyllum leaves. 
MATERIAL AND OBSERVATIONS 
In the present experiment twelve young Bryophyllum 
calycinum plants were set out on benches in the greenhouses at 
Columbia University. These were rapidly growing plants with 
numerous leaves of all ages, although none were very old. Only 
the young leaves in the middle portion of the plant were used. 
Five to ten of these leaves in each plant were selected. The 
inoculations were made by piercing the notches of the middle 
portion of the leaves where shoots most frequently develop 
(Loeb 1918 a) with a needle dipped into a sub-culture of the hop 
strain of Bacterium tumefaciens. The inoculations were made 
on September 25, 1923. The leaves were carefully labeled. 
They were examined from time to time and all changes were 
noted. On April 21, 1924 it was observed that the inoculated 
leaves were becoming old and dying. The leaves were de- 
tached and the numbers and kinds of crown galls were recorded. 
FIG. I represents a crown gall with four leafy shoots resulting 
from the inoculation of Bacterium tumefaciens into the notches 
of the leaf. It is quite clear from this photograph that where 
the inoculations were made globular crown galls developed, 
with the exception of one case shown here, where the bud at 
the notch developed into four shoots. At the bases of these 
shoots a large crown gall is to be seen. Such leafy crown galls 
are like those that sometimes develop when the axillary bud of 
the stem is inoculated with B. tumefaciens, such as shown by 
