43 * 
Journal of Agricultural Research 
Vol. XXVI, No. 9 
shattering. The points on the stems where the “primary galls” appeared 
had been raised to about 5 feet from the ground. Although a large 
number of these “primary galls” showed evidence of elongation, good 
“secondary galls” were secured on only about 6 per cent of the plants. 
These appeared sometimes on the leaf petioles and sometimes in the pith. 
The influences of heavier or lighter infection in the rapidly elongating 
region of sunflower, similar to those noted in sweet pea, may be seen in 
Plate 5, A and B. In A the infection involved 15 internodes and 
prevented their normal expansion, so that the galls remained in a more 
or less compact group. On the contrary, in B the infection was not so 
heavy, and expansion was obstructed in only the lower ones of all the 
internodes involved. Here are found “secondary galls” c and d appearing 
on the petiole of a leaf which is removed from the “primary gall” b by 
13 intemodes and a distance of 49 cm. Sections cut through the petiole 
one-half cm. below d showed a “tumor strand” directly in line with the 
“secondary gall.” This strand consisted of cortical tissue which had 
been modified by the presence of the bacteria so that the walls have a 
different staining reaction. Limited regions of hypertrophy and still 
more limited areas of hyperplasia were found. 
“Tumor strands” were also found in the pith. In Plate 5, C, the dark 
mass of gall tissue which arose about the needle puncture at e may be 
seen. From this a line of tumor tissue extends upward over 60 cm. 
At f the tumor tissue occupied almost the exact center of the pith and 
measured about 3 mm. across. It seemed to be moist and living, while 
the surrounding pith cells appeared dry, white, and dead. Paraffin sec¬ 
tions were cut from the tumor tissue in this position. It proved to be 
composed of a series of “tumor strands” that showed various degrees 
of change. In Plate 5, D, some small tumor cells (g) may be seen sur¬ 
rounded by large tumor cells (h) which have a characteristic staining 
reaction, while pith cells that have been collapsed by the pressure of this 
and other strands may be seen at i. In figures E and F of the same plate 
a larger group of small tumor cells may be seen at g. Here vascular 
elements have developed at j. 
Inoculation experiments on tobacco, though limited to 50 plants, 
produced rather similar results. In most cases, as was noted in the sun¬ 
flower, there was considerable elongation of the primary lesion. In a 
small percentage of the inoculations “secondary tumors” were secured 
which involved several intemodes. In one case five leaves, separated by 
eleven internodes, were involved as a result of a single puncture inocula¬ 
tion. Two of the leaves were so completely invaded that they appeared 
as irregular masses of gall tissue. The tip of one of these heavily involved 
leaves was separated by 9 cm. from the puncture. 
Similar experiments on the Paris daisy for one reason or another have 
failed. However, such phenomena have been very completely described 
on this plant by Smith (4). The writer is of the opinion that these 
phenomena on the Paris daisy are similar to those on the sweet pea, 
sunflower, and tobacco. 
HISTOLOGICAL STUDIES OF REGIONS OF ELONGATION 
Inasmuch as “secondary galls” have never been secured except when 
the inoculations were made into rapidly elongating regions close behind 
condensed buds, it seemed essential for the understanding of the method 
by which these structures are formed to study the morphology of the 
