Dec, 1921] 
LEVINE — STUDIES ON PLANT CANCERS 
this time to explain the cause for the difference in these crowns. It may 
be suggested that possibly the disturbance of the vascular tissues of the 
root by the crown gall may be responsible for it, but no definite evidence 
is at hand. 
Fig. 9, A, B, C, D. Types of crown gall on the mangel wurzel: A, smooth; B, warty; 
C, smooth- warty condition combined; D, small smooth galls covered with clusters of warts. 
The weights of the inoculated and uninoculated mangel wurzel show 
similar conditions. The average weight of the uninoculated mangel wurzel 
grown in these cultures is 113.47 g- The weight of the root is 52.09 g., and 
the average weight of the crown is 61.38 g. 
The average weight of the inoculated plants, samples of which are 
shown in figure 9 with the smooth, warty, and mixed galls, is 124.38 g. 
(see table 4), which is far above the average weight of the normal plant. 
The weight of the plant without the mass of the crown-gall tissue is 84.31 g., 
while that part of the crown gall that could be removed from the root 
averaged 39.91 g. The average weight of the root is 41.69 g. and of the 
crown 42.78 g. The average weight of the root and its crown gall is 81.6 g. 
Here again the crown gall increased the weight of the root as in the other 
cases mentioned above; while the weight of the leaves in the inoculated 
plants was considerably lower, the growth of the root overcame the difference 
so that the average weight of the entire inoculated plants was greater than 
that of the normal plants. 
It may be of further interest to note that the crown galls in the mangel 
wurzel, harvested approximately two months after inoculation, weighed 
more than the remainder of the root. None of the crown gall tissue on 
the mangel wurzel had disintegrated at the time they were harvested, but 
on being brought into the laboratory and moistened, decay set in at once. 
The crown galls alone turned black, and within 48 hours they were disin- 
tegrating while the normal tissues of the root remained unchanged. 
