July 21,1923 
Crowngall Organism and Its Host Tissue 
125 
In order to determine more clearly whether the bacteria had passed 
up through the tracheae, a tomato stem was tied to a supporting rod and 
then a section several centimeters long was frozen by means of carbon 
dioxid. On the next day the soft tissue had collapsed and dried, leaving 
apparently only strands of dead conductive vessels with the firm covering 
of shrunken tissue about them. This treatment did not cause severe 
wilting of the upper part of the plant, especially when part of the top 
was pruned off. The tissue which had been frozen was allowed to dry an 
additional day to further guard against the occurrence of a moist passage 
for the bacteria outside of the vascular tissue. Then the stem was cut 
off and placed in a suspension of the bacteria (PI. 2, E), as previously 
described. Two hours later the bacteria were recovered in large num¬ 
bers from the interior of the stem above the collapsed area, but not in 
such great abundance as in the earlier experiments. This may have been 
due to a reduction in the flow of sap through the bundles. 
These experiments were modified so that the stem could be cut part 
way through under a suspension of the gall organism. For this purpose 
a cylinder of cork was divided in two and fastened around the stem with 
pins. Upon this as a base was placed a short piece of large rubber tubing 
which had been cut down the side for convenience in locating it around 
the stem. The whole was sealed with vaseline so that it formed a cup 
about the stem (PI. 2, F). This was filled with a suspension of the organ¬ 
ism and a transverse incision was made in the stem below the surface 
of the fluid. The suspension and cup were removed at the end of 5 hours. 
After 48 hours punctures were made in the stem with the tip of a sterile 
knife at intervals from the top down to the cut. Eight weeks later four 
galls had developed out of eight punctures. One of these was 8 cm. above 
the inoculation cut. Four repetitions of this experiment gave like results. 
They produced, in order, three galls from 6 punctures, eight from 14, six 
from 11, and seven from 9. 
While one may not be fully confident of the exact course followed by 
the bacteria, these experiments suggest that, under favorable conditions, 
the crowngall bacteria can pass through the tracheae and induce galls 
at some distance from the point of entry, if they are provided with an 
avenue of escape from the vessels and suitable circumstances for develop¬ 
ment. However, there is no evidence to show that they can produce galls 
if they remain inside these vascular elements. 
To determine whether or not the organism occurs commonly in some 
of the vascular tissue, 60 sterile punctures were made in the stems of 
tomatoes above three-weeks-old galls. Four weeks later not a single 
one showed any evidence of tumor formation. So it may be assumed 
that this parasite may travel in some parts of the vascular bundles if 
conditions are favorable, but that probably it does not ordinarily induce 
infection from this position. 
EARLIER ATTEMPTS TO LOCATE THE ORGANISM 
The experiments so far described have indicated that the crowngall 
organism begins its relations with its host tissues in the liquid occupying 
the intercellular spaces about the wounds. The first striking evidence 
in support of this conception came to the writer's attention in an experi¬ 
ment described on an earlier page. There it was shown that the galls 
developed rather uniformly throughout the water-soaked area produced 
by the puncture and closely coincided with it in outline. So from the 
