Dec, 1921] LEVINE — STUDIES ON PLANT CANCERS 
have no very reliable basis for measuring health or vitality quantitatively, 
it would be generally conceded that plants such as those represented in pot 
"A" are more vigorous and more healthy than those in pot "D." 
On removing the plants from the soil, it was found that the size of the 
Fig. I, a, B, C, and D. Four pots filled with manure, brown silt loam, manure and 
brown silt loam, and sand, respectively. 
leaves generally served as a good indication of the size of the roots. The 
roots whether inoculated or uninoculated were largest when grown in the 
soil and manuie, smaller when grown in brown silt loam or in the combi- 
• nation of the loam and manure, and smallest when grown in sand. 
The size and weight of the crown gall in each case was directly propor- 
tional to the size and weight of the root, as will be shown below. It is seen 
that the weight of the entire plant grown in the four different soils shows 
that those plants which were grown in soil rich in organic material were 
well nourished and attained the greatest weights while those grown in sand 
weighed less. Table i gives the fresh and dry weights of the entire plants 
grown in the four different soils with their roots inoculated with Bacterium 
tumejaciens. Representative plants with their infected roots from each 
group are shown in figure 2. Figure 2, "A" shows an infected root of a 
plant grown in garden soil mixed with an abundance of manure. " B " was 
grown in brown silt loam and manure. "C" was grown in brown silt loam, 
and "D" was grown in sand. As shown in table i, the infected plants 
grown in pots containing garden soil and manure attained a fresh weight of 
46.57 g. and a dry weight of 4.73 g., while plants grown in brown silt loam 
