508 
AMERICAN JOURNAL OF BOTANY 
[Vol. 8. 
to need mention here. Only those papers that deal with the problem at 
hand are reviewed. 
Tumor-like growths on the different varieties of beets have been recog- 
nized in America and Europe for a long time. These growths occur sporad- 
ically. Destructive epidemics are not known. Smith, Brown, and Town- 
send (191 1 ) have shown that at least the gall formation known as crown 
gair^ of the beet is produced by Bacterium tumefaciens. They were able to 
isolate the organism from the tumors on the beet and to infect beets, causing 
the formation of new crown galls. 
Townsend (191 5), studying the crown gall of the sugar beet which 
appears spontaneously in the field , concluded that the galls have no marked 
effect upon the size of the beet. The largest as well as the smallest beets 
may become seriously affected, and it is impossible to know whether roots 
would be large or small if they had been free from the infection. The galls 
begin to appear when the beets are one fourth to one half grown, that is, 
about midsummer; and from that time on they may appear at any time 
until harvest, so that crown galls of various sizes and ages may be found 
on the beets. 
Jensen (191 8) in his investigation of tumor-like growths in plants 
studied both spontaneous crown galls from the common races of beets and 
those that he produced experimentally by inoculation. He concludes that 
in the case of the mangel wurzel the crown gall has no detrimental effect 
upon the growth of the plant. In the garden beet, the tumor attains only 
slight size. In the sugar beet, on the other hand, Jensen finds the disease 
resulting in enormous tumor-like formations, irregular knotty structures 
which in section exhibit a very irregular arrangement of the vascular 
bundles differing markedly from that in the normal portion of the root. 
Jensen does not report on the relative sizes of the galls and roots in the 
sugar beet, nor does he discuss the structural characters of the normal roots 
of the various races for possible suggestions as to the cause of the differences 
in the size and structure of the galls. 
Materials and Methods 
The cultivated garden varieties. Early Model, Egyptian Early, and 
Giant Mangel Wurzel of Beta vulgaris were studied in my experiments. 
A preliminary test of the effect of the soil on the size of the root and crown 
gall produced when the roots were inoculated with Bacterium tumefa- 
ciens was carried out in six-inch pots in which a mixture of Early Model 
and Egyptian Early seeds was planted. Four kinds of soil were used. 
Each kind was placed in 12 pots. The first group was filled with garden 
soil mixed with an abundance of manure that had been previously used for 
mushroom culture. The second contained a brown loam that was obtained 
2 "Tuberculosis" of beets is a tumor-like growth on beets produced by Bacterium 
heticolum (Smith, Brown, and Townsend, 191 1). 
