92 EXPERIMENT STATION. [Jan. 



In the first series, that of the steam-sterilized, it is noticed 

 that a fair yield of potatoes was obtained, and the amonnt of 

 scab on the check and treated tiles was as follows : — 



Check, 40 



Check, . . . . . 18 



Check, 30 



Average, . . . .29 



Per Cent Scab. Per Cent Scab. 



Steam-sterihzed soil, . . 30 



Steam-sterilized soil, . . 41 



Steam-sterilized soil, . . 23 



Average, . . . -31 



These results surely do not show much benefit from steriliza- 

 tion, and on the whole the amount of scab seemed to increase 

 with the sterilization. The reason for this is not apparent, but 

 may be explained in different ways. In all probability steril- 

 izing the soil in open boxes by heating the soil to 210° or 212° 

 E. was not sufficient to kill the germs of scab. It seems hardly 

 probable that if the organisms had been killed by sterilizing, 

 the soil in the pots could have been contaminated to this extent, 

 or that the seed after being treated with formaldehyde could 

 have been the cause of this. 



In the second series a manufacturer's by-product Avas used, 

 which for the present we will call by-product A. This was ap- 

 plied in different amounts and scattered in the soil both in the 

 powder form and as a paste mixed with water. The three 

 checks averaged 44 per cent, scab, and the treated tiles averaged 

 30 per cent, scab, with the lowest amount of scab present in the 

 tile treated with the smallest amount of the by-product A. On 

 the whole, this substance seemed to have some beneficial action, 

 although apparently there were discrepancies in the comparative 

 amounts of scab present in relation to the amounts of the sub- 

 stance used. 



The next series, made up of gaseous formaldehyde treatment 

 by the reaction of potassium permanganate on formaldehyde, 

 gave no results except in one or two instances, and then the yield 

 was very small and in some cases none at all. 



The series of tiles treated with copper sulfate showed that 

 this substance might have a beneficial action in strengths up to 

 1-10,000, but there was the same amount of scab on the tile 

 treated with copper sulfate, 1-1,000, as there was on the checks. 



