6 BULLETIN 818, U. S. DEPARTMENT OF AGRICULTURE. 
DISCUSSION OF RESULTS. 
From a study of the data presented in Table I, relative to the two 
sets of 4-inch pot treatments, the results are here summarized. 
1. As a result of submersion of the soil in boiling water for 2 J, 5, 
and 10 minutes, no infection by root-knot nematodes, Pythium, or 
Rhizoctonia occurred in either set of pots except in one pot which 
showed a small amount of Rhizoctonia root discoloration. As this 
minor infection occurred in one of the pots to which diseased roots 
were added and which received the 2i-minute submersion, it is quite 
probable this was due to insufficient treatment. The plants in the 
check pots showed 83 per cent affected by nematodes and 100 per 
cent severely diseased by the fungous parasites. A comparison of 
the typical appearance of roots from treated pots and those from 
untreated check pots is shown in Plate I, figure 1 . 
2. Normal germination occurred in all treated pots, an average 
of 42 plants per pot, while in the untreated pots the stand was re- 
duced by the soil organisms to an average of 12 plants per pot. 
3. All treatments prevented damping-off in both sets of pots, as 
was shown by the final examination, while in the untreated check 
pots half of the seedlings died after the first germination count made 
two weeks subsequent to planting. (PI. I, fig. 2.) 
4. Throughout the experiment the plants in the check pots showed 
pronounced yellowing and stunting, reaching an average height of 
only 3 inches at the time of the final examination, as compared to 
an average height of 5 to 7 inches for the plants in treated soil, all of 
which were vigorous and of a healthy green color. 
Certain facts evident from a study of that part of the data in Table 
1 pertaining to the two sets of 8-inch pot experiments are here pre- 
sented. 
1. The 18 treated pots showed an average of 74 seedlings per pot 
two weeks after planting, as compared with an average of 22 for the 
two check pots, a reduction of 70 per cent in the stand. The typical 
appearance of treated and untreated pots at this time is shown in 
Plate II, figure 1. 
2. A slight amount of damping-off occurred in two of the six pots 
receiving the 1,000 c. c. treatment, while none was noted in the 12 
pots which received the larger amounts of boiling water. In the 
check pots, however, almost 60 per cent of the seedlings damped-off 
between the first germination count and the final notes. 
3. The plants in the check pots remained markedly stunted 
throughout the experiment, attaining a final average height of only 
2 inches, and were considerably yellowed and unhealthy in appear- 
ance. The plants grown in pots receiving 1,000 c. c. of boiling water 
reached a final height of 3 to 4 inches and were slightly yellow in 
color. The plants in all pots receiving the larger treatments grew 
