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Journal of Agricultural Research 
Vol. XXVI, No. 9 
in that portion of the mother cell nearest the bacteria. Thus a small 
daughter cell is interposed between the bacteria and the remainder of 
the mother cell. This may be seen in Plate i, B. So it appears that the 
new tumor cells form a sheath about the bacteria and indicate the source 
of the stimulus. In the tomato this condition is most evident in galls 
eight or ten days after inoculation. In the later stages, in many cases, 
such a confusion of proliferating tissue appeared that the original rela¬ 
tionships were lost. 
Whether or not the bacteria were able to migrate through the tissue, 
beyond the intercellular spaces which were water-soaked at the time of 
infection, has not been definitely determined. The writer has never 
found any evidence to indicate that the bacteria might pass through the 
tissue in any manner other than through the intercellular spaces. It 
appears that they can influence the cell walls a short distance from the 
intercellular space so as to produce the yellowing previously mentioned. 
However, there is every reason to believe that the extent of the original 
invasion might be enlarged by any influence, such as injury or sudden 
change of temperature, which would cause liquid to occur in the inter¬ 
cellular spaces. It also appears that if the area of original invasion were 
one that was rapidly elongating, then this area might be stretched out 
over a considerable distance and the infection would then appear as a 
long-drawn-out tumor or “ tumor strand.” This type of gall may appear 
when an inoculation is made into the region of elongation near a con¬ 
densed bud such as one finds in sunflower, sweet pea, Paris daisy, and 
tobacco. The elongated tumor is sometimes manifested as a “ primary 
gall” with one or more “secondary galls” and “tumor strands.” 
DEVELOPMENT OF “TUMOR STRANDS” AND “SECONDARY TUMORS” 
“Tumor strands” and “secondary tumors” have not been easy to pro¬ 
duce. Several thousand inoculations have been made on tomato, rasp¬ 
berry, blackberry, tobacco, sunflower, Paris daisy, and sweet pea on parts 
other than the rapidly elongating regions. These produced galls readily 
but never produced any “secondary tumors.” These phenomena never 
have been secured except in cases where the puncture was made close, 
behind the growing point of a condensed bud such as occurs in sunflower, 
tobacco, sweet pea, and Paris daisy, but not in tomato. Even in these 
instances the number of “secondary tumors” secured was seldom above 
5 per cent of the number of inoculations. The most favorable position 
for making inoculations to secure “secondary tumors” is described by 
Smith (4, p. 23 ), “At the time of inoculation the stems were soft and 
rapidly elongating, and the needle pricks were made in what was then 
the top of the plant.” But so far as the writer has been able to ascertain, 
none of the previous workers on crown gall have taken into account the 
influence of either (1) the water-soaking of the intercellular spaces or (2) 
the elongation of the condensed bud 4 in the production of “secondary 
tumors.” 
On February 7, 1922, a number of inoculations were made with a fine 
needle in the rapidly elongating buds of some Spencer sweet peas grown 
in the greenhouse. On about the fifth day thereafter, distinct swellings 
4 After this manuscript was submitted to the publisher an article was received by robinson, w., and 
WALKDRN, H. A CRITICAL STUDY OR CROWN GALL. /» Ann. Bot., V. 37, P- 299-324, 4 figs., pi. 5-6. 1933. 
Literature cited, p. 322-323. It was noted with satisfaction that in this publication conclusions very similar 
to our own upon the relation of the elongation of the growing tip to the development of “tumor strands” 
and related points were reached independently by these authors. 
