Dec., 1923] 
SHERWOOD — FUSARIUM WILT OF TOMATO 
541 
most cases were quite clear. Some, however, were more or less turbid; 
hence, to avoid probable errors in making color comparisons, the turbidity 
was reduced by dilution. Five-cc. portions were placed in test tubes of the 
same diameter as those containing the buffer solutions, and each portion 
diluted with 5 cc. of water. The indicator solution was then added, 
admixed, and the color resulting was compared with the colors obtained on 
adding the same quantity of the same indicator to 10 cc. of the various 
buffer solutions of known hydrogen-ion concentration. A comparator was 
used in making the color comparisons. Whenever possible, checks were 
made by using different indicators. Checks were also made by using the 
soil extract without dilution, but in no case were the results found to vary 
appreciably. Clark and Lubs (1) found that a much greater degree of 
dilution than was used in these tests has such a small effect on the hydrogen- 
ion concentration that it can seldom be detected by the colorimetric method. 
Experiments with Tomato Seedlings in Infected Soil 
Experiment-1 
In his preliminary work Clayton ( loc . cit.) arranged a series in which 
equal quantities of the two types of soil were treated with successively 
increasing quantities of calcium carbonate as shown by the following record: 
Number of 
Flat Treatment 
Sandy Loam Soil Silt Loam Soil 
1 . No treatment No treatment 
2 . 11.1 grams CaCCb 22.5 grams CaC 0 3 
3 . 22.5 “ “ 45.0 “ 
4 . 45-0 “ “ 9 °.o “ 
5 . 90.0 “ “ 135.0 “ 
6 . 135-0 “ 
The treatment above described had been given the soils several months 
prior to the time when the writer assumed charge of the experiments. The 
flats used were about four inches deep, and large enough to allow fifty plants 
to grow for a period of from four to six weeks without too much crowding. 
In addition there was added to each series a flat of soil in which an 
attempt was made to secure a more acid condition than that which existed in 
the naturally acid soils of flats no. 1. Twenty cubic centimeters of con¬ 
centrated hydrochloric acid was considerably diluted, poured over the sur¬ 
face of the soil, and thoroughly admixed. These flats were designated 1 A. 
Sterilization was accomplished by autoclaving the soils at fifteen pounds’ 
pressure for two hours. The flats were then allowed to stand for three days, 
when the soils were reworked and inoculated, and Chalk’s Early Jewel 
tomato seed was planted in rows. The planting was thick enough to insure 
a good stand so that the plants could be thinned out to the desired number 
in each flat. 
In all the experiments the soil was inoculated in the following manner. 
