40 HATCH EXPERIMENT STATION. [Jan. 



so through both ends of the tile, and only a little through 

 the pores. 



In these experiments it appears that a two-inch pipe is far 

 superior to a one-inch pipe as a heater, where the number 

 and size of the perforations are the same ; also that for all 

 practical purposes one-fourth-inch perforations are better 

 than smaller ones, even where the total area is the same or 

 even greater. It is therefore not so desirable, if eiEciency 

 is to be considered, to construct sterilizers out of one-inch 

 iron pipe, as some have done, inasmuch as a two-inch tubing 

 with tliree-sixteenths or one-fourth inch perforations will 

 give better results. The best results were obtained with a 

 section of Cartter's tube, which contained four rows of per- 

 forations one-fourth inch in diameter. 



In heating soils there are many factors which have to be 

 taken into consideration, such as the pressure and the amount 

 of steam supplied, the size of the apparatus, and the amount 

 of earth that is to be heated. These factors are so variable 

 that probably no two men have sterilized soil at the same 

 cost. Sterilizers that will do rapid and cheap work at a 

 certain pressure and supply of steam will do less work at a 

 greater cost with the same pressure and less volume of steam. 

 It is not only essential that the sterilizer should be constructed 

 on the best principles, but the volume of steam and pressure 

 maintained should be adapted to the requirements. 



Influence of Sterilized Soil on Seed Germination. 

 In previous reports and bulletins from this station there 

 have been given results of some experiments relating to the 

 influence of various agencies upon the germination of seeds. 

 For some years much use has been made of sterilized soils 

 by this division in studying the various diseases of green- 

 house crops. In numerous experiments, made upon a con- 

 siderably large variety of plants, we have always noticed 

 the marked effect which sterilization had upon the germina- 

 tion of seeds and the subsequent growth of the })lant. Many 

 photographs have been made from time to time of those crops 

 which display very important differences, and in some in- 

 stances the weight of the plants lias been recorded, which 



