20 



against 30% in the normal or untreated plot. This experiment 

 shows also in favor of f in. of sterilized sand.* 



Both the sand plots show cleaner lower leaves which are much 

 more free from decay (Botrytis Rot) than any of the untreated ones. 

 A similar experiment to that just described is shown in Diagram II ; 



n.l 



n.2 



n.3 



• = Drop 



Diagram II. Similar to I. n. i, n. 2, and n. 3, normal or untreated plots, a, 4 in. of 

 sterilized soil, b, I in. of sterilized sand, c, i in. of sand, d, J in. of coal ashes. 



which followed that given in Diagram I. In this case the soil was 

 purposely contaminated throughout by forking it over after the pre- 

 ceding experiment had been completed ; in addition to this, another 

 bed containing 264 plants was inoculated, and the plots treated with 

 heat, sulphur, and lime. The infection in this experiment is about 

 the same as in experiment i. The | in. of sterilized sand is how- 

 ever scarcely better than the same amount of unsterilized sand, 

 which gives practically the same result as | in. coal ashes, while 

 4 in. sterilized soil was entirely free from Drop, 



The covering of one plot with a thin layer of powdered charcoal 

 and two others with similarly covered layers of sulphur and lime did 

 not produce favorable results, and they will therefore not be consid- 

 ered here. In experiment 3, (Diagram III) we have a slight modi- 

 fication of the two preceding ones with an additional amount of 

 infectious material in the soil. A period of some five months 

 elapsed between this experiment and the preceding one ; in the 

 meantime a crop of tomatoes was grown in the soil. The | in. cov- 



*The term sterilized is employed throughout this work in a relative sense and has reference 

 only to the Drop fungus. A large number of microorganisms still survived after heating, con- 

 sequently absolute sterilization was not accomplished in any instance. The heating was 

 done by steam, as described in Bull. 55 from this station. 



