238 LEVINE: STUDIES ON PLANT CANCERS—IV 
produced growths which averaged 0.4 cm. larger than the dilution 
which was three times the strength of the first. It seems from 
these studies that for uniformly aged cultures and equally well 
developed plants a drop of the weakest suspension used when 
inoculated into the stem or midvein of a tobacco plant incites 
a crown gall development as large as a suspension forty times 
more concentrated.* 
COMPARISON OF THE REACTIONS OF DIFFERENT PARTS OF THE 
PLANT TO EQUAL QUANTITIES OF THE SAME DILUTION 
Striking differences were found among the crown galls re- 
sulting from inoculations with equal quantities of the same or 
similar dilutions of Bacterium tumefaciens when placed in dif- 
ferent parts of the plant. This appeared to be true regardless 
of the quantities of bacteria or strength of the emulsion used. 
The crown galls on the midveins of leaves were invariably smaller 
than those on the stem and these in turn were smaller than those 
that developed at the axil of a leaf. The inoculated axillary 
bud of a decapitated plant produced generally the largest crown 
gall. 
For example, the sizes of crown galls obtained with Emulsion 
II a, b, and c on the leaf vein and the stem show that equal 
quantities of bacteria produce in the stem a neoplastic growth 
considerably larger than on the midvein of the leaf. Comparing 
the tumor growths in the leaf axils with those of the stem inter- 
node produced by equal quantities of the same emulsion (see 
TABLE, Emulsion I) shows a slightly larger growth in the axil. 
The inoculation of Emulsion Ia into five stem internodes pro- 
* Since the above data met Sra tne en ~ had the Sppeckuaity: | to — 
further, weaker 
cula- 
tions of one drop and 0:5 ce. ce hos shidon at the leaf axils of Sas Ek 
nium plants. I used 3 cc. of the scrapings of a twelve day culture of Bacterium 
tumefaciens and suspended 1 cc. in 500, 750, and 1000 cc. of sterilized tap 
water. 
The plants which received 1 drop or 0.5 cc. of the 1:500 solution produced 
small crown galls which averaged 4 mm. in diameter forty-five days after the 
inoculation. The plants which received 1:750 and 1:1000 solution, in only a 
very small percentage of inoculations, were crown galls produced. Those that 
developed were approximately 3-4 mm. in diameter, and in general, were 
equal in size to those produced by inoculations with undiluted Bacterium 
tumefaciens 
