285 



veniently called permanent and temijorary changes. By permanent changes 

 are meant those which have become fixed in the plant and are due to gen- 

 eration after generation being subject to the same conditions. By tempo- 

 rary changes are meant those which have taken place for only a genera- 

 tion or two and which have not become impressed upon the plant to such 

 an extent but that it will again revert to the normal on being placed under 

 the former conditions. To this latter group belong the temporary reduc- 

 tion of leaf surfaces, stunted growths, and other similar changes. It is 

 only this latter group which can possibly figure in the work carried on. 



The study of the gross changes, due to the variation of soil conditions, 

 has always been one of great interest to the botanist. These changes may 

 be seen in nature all about us and often the vegetation of a region will 

 give, to the trained eye, the conditions of the soil. The soil is now 

 studied, not by chemical analysis, but by what will grow upon it. 



The object of the experiment has been to determine whether these 

 variations in the soil have given other than gross changes. Although the 

 minute differences were the main object in view, all gross changes, which 

 occurred, were noted in order to trace their connection with the minute 

 ones. 



The soils used in the experiment were a good, dark loam, a good yel- 

 low clay, and a clean pit sand. 



The loam used contained only a very small quantitj- of sand and was 

 taken from a field which had been under cultivation for a number of years, 

 but to which little or no manure had been added for some time. It 

 contained a large amount of silt and humus. 



The clay also contained a veiy small quantity of sand and was secured 

 only a short distance from a brickyard. The soil, however, was a little 

 too light for brick-malving. 



The sand was a clear pit sand, not over sharp or very coarse. On 

 washing it showed very little silt or foreign substances. 



The other three conditions, temperature, light and moisture, were 

 kept, as nearly as possible, uniform for all. 



In watering, great care was taken to keep them in tlie best growing 

 condition. The plants were only given water when they required it, so that 

 in no case were they overwatered or allowed to dry out more than 

 possible. 



