July 21, 1923 
Crowngall Organism and Its Host Tissue 
131 
tically pure cultures of the crowngall bacteria, which were identified by 
successful inoculations. 
From the foregoing observations and experiments we believe it may 
safely be concluded that the crowngall bacteria are located in certain 
intercellular spaces of the host tissue, and that they are present in larger 
numbers than has been supposed. 
No attempt has been made in this paper to describe the responses of 
the host to the bacteria in the intercellular position. These activities, 
with special emphasis on the formation of the ‘‘tumor strands,” will be 
treated at a later time. 
SUMMARY 
(1) Crowngall infection in tomato stems was found to take place 
only through wounds. 
(2) It was not found to be necessary for infection that the organisms 
should be carried into the tissue at the time of puncture. Successful 
results followed their application to the surface of wounded tissues. 
They were observed to have a positively chemotactic response to ex¬ 
pressed tomato sap, which could account for their entrance following 
surface application. Under favorable conditions infection was induced 
by organisms applied to the surface as long as seven days after the 
puncture. 
(3) When needle punctures were made into turgid tomato and tobacco 
stems, the intercellular spaces above and below for several millimeters 
became occupied by liquid and appeared water-soaked. When puncture 
inoculations were made, the galls which developed were found to coin¬ 
cide closely in outline with these water-soaked regions. 
(4) Galls of different sizes were induced experimentally by varying 
the sizes of the inoculating needles and consequently the extent of the 
water-soaked areas. 
(5) A half hour after inoculations were made in the usual manner by 
punctures, a red-hot needle was inserted in the path of the inoculating 
needle. It is believed that this destroyed all the cells that had pre¬ 
viously been ruptured. The subsequent development of galls from the 
outer margin of the water-soaked region is interpreted as indicating that 
the bacteria are not dependent upon gaining access to ruptured cells, 
and is, on the other hand, consistent with the idea that they are dis¬ 
tributed in the liquid in the intercellular spaces. 
(6) When a continuous channel of liquid was provided in the tomato 
stem either by mechanical pressure or by freezing, the bacteria migrated 
and produced galls several centimeters from the point of inoculation. 
The subsequent gall development occurred over the area approximately 
corresponding to this original water-soaking of the tissue. 
(7) When the organisms were introduced into a wound which cut 
some of the vascular bundles, they appeared to travel in some part of 
the conductive tissue, probably the tracheae, and when a wound enabled 
them to escape, induced proliferation. This type of infection is not 
considered a common occurrence in nature. 
(8) The usual methods of staining failed to demonstrate the bacteria 
in situ. This appeared to be due to the staining of the adjacent cell 
walls and of the substance which occurred in the intercellular spaces 
which was of similar intensity to that of the bacteria, thus masking them. 
