8O THE SOIL SOLUTION 



been under observation for two years. The soils were of the same 

 type, Cecil clay, and were so similar in their physical charac- 

 teristics as to be distinguished with difficulty in the laboratory. 

 On one field a good crop of wheat was grown, followed by a 

 good crop of clover and tame grasses. On the other field, the 

 corresponding crops had been quite poor. The field yielding 

 the good crops had been plowed somewhat deeper, and had 

 previously received a moderate application of stable manure. 

 Otherwise, so far as could be learned, the cultural history of the 

 fields had been the same. For convenience, the sample from 

 the first field will be designated "good," and from the other 

 "poor." 



Aqueous extracts from these soils were prepared, the same 

 proportion of distilled water to soil being taken in each case, 

 and the time of contact being the same. The solutions were 

 freed from suspended matter by being passed through Pasteur- 

 Chamberland bougies under pressure. Young wheat seedlings 

 germinated at the same time, and selected carefully for uni- 

 formity of size and apparent vigor, were grown in these solu- 

 tions for three days. At the expiration of this period the seed- 

 lings in the extract from the good soil were about five inches in 

 height, and the roots were clear, clean and turgid. The plants 

 in the poor extract were scarcely three inches in height, and the 

 roots were assuming a slimy, unhealthy appearance and becom- 

 ing flaccid at the tips. The plants were then all removed, the 

 roots washed carefully in tap water; the plants which had been 

 in the poor solution were placed in the good solution, and those 

 which had been in the good solution were placed in the poor solu- 

 tion. At the end of four days further, the poor plants had sur- 

 passed in height the ones which had previously been in the good 

 solution, and the roots had acquired the general characteristics of 

 healthy plants. These which had been originally in the good 

 solution and then transferred to the poor, had made little addi- 

 tional growth, and the roots had become somewhat flaccid. 1 



This experiment was repeated several times, not only with 



*The success of this and of many of the following experiments was 

 due in large measure to the skill and patience of Mr. James E. Breazeale. 



