RELATIONS BETWEEN THE SOIL AND HIE PLANT. 75 



They all enter through the roots, having always 

 been previously dissolved in water. If they were 

 received in fine solid particles, the ash of any particu- 

 lar plant would be different according to the differences 

 in various soils; but this is not found to be the case, 

 as each plant has a peculiar ash of its own. 



a. Experiments have been made by preparing six 

 different plots of ground in the same manner, and then 

 mixing with one alumina, with another lime, with 

 another soda, with another magnesia, and so on; all 

 of these substances being reduced to a very fine pow- 

 der. The result was that the ash in the same plants 

 grown on all of these plots, was nearly identical in 

 composition; thus showing that they did not take in 

 every thing in the shape of fine particles that came in 

 contact with their roots, but received their food in 

 solution, and even then only such as suited their 

 particular wants. 



It may be best here to explain that a substance 

 spoken of as in solution is dissolved, according to the 

 common acceptance of the word, just as sugar or salt 

 is dissolved in water. 



The fertile soil then must contain all of these in- 

 organic substances, because plants will not flourish 

 without them. a. Alumina does not enter into plants 

 to any appreciable extent, but is necessary to them for 

 reasons which have been mentioned when referring 

 to the stiffness and physical structure of the soil 

 b. Manganese can not be considered indispensable to 

 the ordinary crops, but there are some classes of trees 

 which appear to require it in considerable quantities. 

 The others on the list are found in all cultivated crops. 

 The following table gives instances in three common 

 ones : the analyses were made in Germany. 



