Wire Stem of Cabbage 37 



The tared culture vessels were maintained at constant weight by weigh- 

 ing every day or two, depending on the rate of evaporation and trans- 

 piration, and adding the necessary water. Five moisture series were 

 maintained for each tank, with five culture vessels for each series. By 

 this method the moistures in each series in each tank were comparable to 

 their respective series in the other tanks maintained at different tem- 

 peratures. One jar in each moisture series was kept as a control. Instead 

 of having only four plants for each culture, from twelve to fifteen seedlings 

 were transplanted into each vessel. Thus from forty-eight to sixty plants 

 were growing at each moisture series at each of the three temperatures, 

 not including the culture vessel with the fifteen control plants. The seed- 

 lings were allowed to become established (six to eight days) before inocula- 

 tion. The method of inoculation consisted in placing a grain of wheat, 

 upon which the fungus was growing, about one-quarter inch below the 

 surface of the soil and about that distance from the stem. This per- 

 mitted the fungus to grow through the soil to the seedling. Several cubic 

 centimeters of water was added to the seedlings at the time of transplanting, 

 to insure their growth. Probably very little of this moisture remained 

 at the base of the seedlings at the time of inoculation^ Obviously, since 

 gravity limits the capillary ascent in a progressive ratio, 14 the surface of 

 the soil must have been considerably drier than the bottom layers, and 

 the figures given in the tables are but an approximation for the entire 

 culture vessel, and not for the surface layer, where damping-off actually 

 takes place. It is further to be pointed out that since the Hilgard 1-centi- 

 meter-column method is a laboratory procedure and the soil used is not 

 in its normal structural state, figures thus obtained may be from 30 to 

 130 per cent too high. 15 To determine the amount of water actually 

 required to saturate a column of soil as high as the column used in the 

 culture vessels, a tin pail, of the same size as the jars and with the bottom 

 perforated, was filled with soil to the same height as that in the culture 

 vessels and then set in water, which was allowed to seep through the 

 perforations. After this had drained for a short time, the weight of water 

 taken up was determined. Numerous determinations of this kind indi- 

 cated that the error introduced by the centimeter-cup method was approxi- 

 mately 70 per cent. The maximum amount of water required to saturate 

 the soil as determined by the Hilgard 1-centimeter-column method was 

 85 per cent of the dry weight, while but 51 per cent saturated a column 

 of soil as high as that used in the culture vessels. In the tables the moisture 

 contents are expressed as determined by the standard Hilgard method. 



The results are tabulated in tables 10 to 15. Inspection of the tables 

 shows that the results of these trials, in the main, agree with those of the 

 preceding year. It is not necessary to discuss each of the experiments in 



" Hilgard, E. W. Soils, p. 208-209. 1911. 



15 Lyon, T. Lyttleton, and Buckman, Harry O. Tbc nature and properties of soils, p. 162-163. 1922. 



