AMERICAN JOURNAL OF BOTANY 
[Vol. 8, 
were next highest with an average weight when fresh of 33.17 g. and a dry 
weight of 3.32 g., and the plants grown in a combination of loam and manure 
fell slightly short of the weights attained in the loam alone. The difference, 
however, is slight. A striking difference is seen in the proportionate size 
Fig. 2, A, B, C, and D. Roots of beets grown in pots filled with manure, manure and 
brown silt loam, brown silt loam, and sand respectively. 
of the crown galls on the roots shown in figure 2, "A" and "D," and also 
in the average weights of the plants which are grown in the garden soil and 
sand respectively (see table i). These results are quite striking and indicate 
rather clearly that the better nourished host responds to the parasitic 
infection more actively than the poorly nourished one, a fact which is 
generally recognized in animal pathology. 
Better nutrition of the host does not tend to increased resistance to the 
growth of an inoculum of an animal tumor, but appears rather to have the 
contrary effect as shown by Ewing. It appears from these experiments 
that when the host is well fed the parasite is also well fed, it reproduces 
more actively, and produces a greater quantity of toxin which apparently 
calls forth relatively a greater hyperplasia of the host. The case is very 
clear here that normal development of the host rather favors the develop- 
ment of the crown gall. There is no evidence of increased resistance to 
the parasite in well grown as compared with poorly grown plants. 
Results of the Field Experiment 
As mentioned above, similar seeds of Beta vulgaris, varieties Early Model 
and Egyptian Early, were planted in two plots, "E" and "SW, " with an 
