July 21 , 1923 
Crowngall Organism and Its Host Tissue 
123 
For the purpose of determining whether punctured cells were nec¬ 
essary for the development of a tumor, the following experiment was 
devised. Thirty inoculations were made into tomato stems in the 
usual manner. After 24 hours a red hot needle was passed through the 
stem in as nearly as possible the position occupied by the inoculating 
needle. This treatment killed not only the cells that had previously 
been injured but also all those around the puncture for approximately 
1 mm. in every direction. Sixty more inoculations were treated in the 
same manner, except that the burns were made at the end of an hour. 
In each case 30 controls were burned. After two weeks 100 per cent 
infection was found developing above and below the burned inocula¬ 
tions, while the controls showed no signs of proliferation (PI. 1, I to K). 
This experiment was repeated on 40 more punctures, with the varia¬ 
tion that the bacteria were applied with a camel’s-hair brush to the 
surface of the bum. Here also 100 per cent infection was secured above 
and below the burn. It seems unlikely that any cells which had been 
able to survive the heat could have had injuries in the walls through 
which the bacteria might have entered. These experiments indicate, 
therefore, that the bacteria exert their influence from some position 
outside the cells. This position, to begin with, at least, is probably in 
the liquid which penetrated the intercellular spaces following the puncture. 
MIGRATION OF THF ORGANISM 
In order to understand more clearly the relations of the organism to 
the liquid in the intercellular spaces, it seemed advisable to make observa¬ 
tions on its motility both in water and in expressed plant juice. 
For studies in water, bacteria from a two-day agar culture were 
mounted in sterile distilled water in a hanging-drop preparation. Ob¬ 
servations were made on the length of time it took motile bacteria to 
move across the field of the microscope. No correction was made for 
the deviation of the bacteria from a straight line. The average of a 
dozen measurements showed them to move at approximately the rate 
of 1 mm. in one minute. Repetition of these measurements gave con¬ 
firmatory results. 
Similar tests were made in which expressed tomato sap was substituted 
for sterile distilled water. The motility of the organism did not appear 
to be materially changed so long as the preparations were fresh. How¬ 
ever, the organisms in the tomato sap retained their motility longer than 
those in the sterile distilled water. 
This gives an easy explanation of how the organisms might reach the 
limits of the region flooded with the liquid which was released by the 
puncture. Further studies of the range of migration were made in 
relation to extensive wounds caused both by mechanical crushing and 
by freezing. 
Large wounded areas were produced on the stems and petioles of seven 
tomato plants by pressure from a glass rod. These bruised areas were 
made on one side of the stems and extended for longitudinal distances 
varying from 4^ to 10 cm. Crowngall bacteria were then introduced 
by a needle puncture into the lower portion of the injured region of five 
of the plants, while two were retained as controls. After four weeks, 
continuous well developed galls had extended for several centimeters 
above the puncture that had received the bacteria (PI. 2, A, B). In no 
