1902.] PUBLIC DOCUMENT — No. 33. 77 



grown in sterilized soil are always lighter colored and more 

 tender, and it is not a difficult task for an expert to pick 

 out such plants in the market. Neither is it difficult to as- 

 certain, from market specimens, to about what temperature 

 lettuce plants have been subjected. In this respect the dif- 

 ferences in plants are marked in a house where the soil has 

 been treated twice as long in one place as in another. A 

 gardener can readily pick out such places. It will be no- 

 ticed in the table that there is 2.2 per cent, more water in 

 tin' plants grown in the treated soil than in the untreated 

 soil, and also that there is a corresponding decrease in the 

 unburned residue which represents the organic matter, ash, 

 constituents, etc. From the color and texture of lettuce 

 grown in sterilized soil, this might be expected. The 

 differences as shown in the above figures only represent 

 one analysis. 



The effect of sterilization on the soil is well illustrated in 

 the case of a market gardener who picked 31,060 No. 1 

 cucumbers from 300 plants. The plants of this crop were 

 carried through in treated soil from the beginning, i.e., the 

 seeds were sown in sterilized soil, and the various trans- 

 plantings were made under similar treatment: The crop 

 was grown after lettuce in the spring, when, it is true, 

 cucumber vines bear heavily. Nevertheless, this was a 

 phenomenal crop at any season of the year, and one which 

 I have never seen equalled. Some allowance must be made 

 in the size of this crop for the strain of cucumbers cultivated, 

 which was a carefully selected stock of heavy bearers. 

 Cucumber plants, nevertheless, respond quite remarkably to 

 the influence of treated soil. 



A number of methods of treating soil with heat have been 

 employed by practical greenhouse men, and many experi- 

 ments on different methods have been made by this division 

 during the last few years. We have been able to observe 

 the efficiency and practical utility of these various methods, 

 and have reported on them at different times. The method 

 of treating the soil by steam to the distance of one foot or 

 more in depth has always appeared to us as the best one to 

 be employed, and, since the cost of such treatment has been 



