102 ROOTS 



suspending them by means of cotton wool, so that their 

 roots shall dip below the surface of the liquid in each 

 bottle. 



In one bottle place distilled water or rain water; in the 

 other soil water. The latter may be obtained by thoroughly 

 mixing common rich garden soil with water and allowing 

 it to stand until all sediment has settled and the water has 

 become clear. 



Place both plants for some time in a locality favorable 

 for growth. After a few days or even hours note any dif- 

 ference in appearance of the plants. 



Which is the -more vigorous in its growth ? Why ? 



Replenish each bottle with the kind of water which be- 

 longs in it, and note the result after several days. 



Note. If rain water is used, it should not be taken from cisterns 

 or rain barrels, since roof drainage frequently contains mineral and 

 organic matter which has gathered as dust on the house tops. If 

 distilled water is not at hand, melted artificial ice is an excellent 

 substitute. 



9'6. ROOTS 

 Object. Same as in Experiment 95. 



Method. Repeat Experiment 95, using various solutions 

 of saltpeter, making the solution in one bottle very weak 

 and the others much stronger. 



After a short time examine the two plants. What has 

 been the result? If several such bottles are arranged, the 

 first containing distilled water only, the second having 

 but a drop of saltpeter in it, the third, fourth, and fifth hav- 

 ing greater amounts, the results will be more definite. This 

 will explain why the farmer does not give too much fertilizer 

 to his plants. 



