4 
452 LEVINE: CROWN GALL ON BRYOPHYLLUM 
Smith (1921, f. ror) and in my own studies on tobacco (Levine 
1923, f. 13, 14). To test whether or not these shoots are diseased 
or only stunted, owing to interference with their water and 
other food supplies by the crown gall tissue, I removed them 
from the leaf. All parts of the mother leaf were trimmed away 
from the crown gall and the leafy shoots attached to it. No 
roots were at this time visible. The adventitious leafy crown 
gall was then planted in a pot. Fic. 2 represents this leafy 
crown gall two months later. It shows the leaf and stem portion 
of the crown gall developed into an apparently normal plant 
with four stems, at the bases of which may still be seen the 
globular portion of the crown gall. Long, fibrous roots have 
developed not only from the surface of the crown gall tissue but 
also from the lower nodes of the stems. The plants grew rapidly 
and are still growing in the experimental garden at Montefiore 
Hospital. 
The other types of crown gall are represented in Fic. 3— 
at a, the globular type, and at b, the differentiated leafy crown 
gall. The crown gall at 6 first appeared as a mass of globular 
tissue. Later the leaves began to make their appearance, as 
described previously in my studies on tobacco. These leafy 
shoots are not due to injury of the dormant bud at the notch 
of the leaf. When the bud is cut into a number of parts at the 
time of inoculation, each part develops into a shoot, as I have 
pointed out and figured before (Levine 1923, f. 16). In the 
present instance, as in the case of Smith’s Fic. 103 (1921) the 
crown gall cells became differentiated and developed into the 
small leaves and stems shown there. Under moist atmospheric 
conditions roots may also appear. It is barely possible that 
five pricks of the inoculating needle will cut up the bud into 
fifty or more parts which develop into small leaves frequently 
sessile. 
Smith (1921) believes these leafy crown galls are embryomata 
comparable to embryomata in human cancer. He considers the 
internal differentiated tissues of the crown gall comparable to 
the stroma of cancer. The stroma of human and of animal 
cancers arises from muscle, nerve, blood vessel, and other con- 
nective tissue elements, which occur in the region of the neoplasm. 
By resumption of growth of these tissues the stroma is formed. 
Vessels and tracheids in plants once formed cannot resume 
