184 FIRST TEAE SCIENCE 



Experiment 88. Fill three 2-quart fruit jars each about half full of 

 distilled water. Add to the water in the first of these gram of 

 potassium nitrate, gram iron phosphate, -ffo gram calcium sulphate 

 and y 1 ^ gram magnesiutn sulphate. Add to the water in the second 

 jar the same ingredients with the exception of the potassium nitrate. 

 Replace this by potassium chloride. Put the three jars where they 

 will receive plenty of sunlight and warmth and place in each a slip 

 of Wandering Jew about 10 inches long. Note which slip grows 

 the most thriftily. In the third jar there is no mineral food, in the 

 first all of this food which is necessary and in the second all the 

 necessary food except nitrogen. 



In Experiment 88, it was found that in the distilled water 

 the plant made but little growth. It did not thrive when 

 the nitrogen was lacking, but grew very well when all the 

 necessary- elements were present. All plant foods must 

 be in dilute solution before plants can appropriate them. 



Experiment 89. In another fruit jar make a strong solution of 

 potassium nitrate or, as it is commonly called, saltpeter. Place in this 

 a slip of Wandering Jew as was done in the previous experiment. 

 Does the slip grow well ? It has a great abundance of nitrogen, which 

 was found so important. Place in a similar strong solution a grow- 

 ing beet or radish freshly removed from the ground." Notice how it 

 shrivels up. Place a similar beet or radish in water. It is not similarly 

 affected. What is the effect of strong solutions on plants? 



If the solution is too strong, as seen in Experiment 89, 

 the plant cannot use it. This is the reason many alkali 

 soils will not support plants. The alkali salts are so 

 readily soluble that the soil water becomes a solution 

 stronger than the plants can use. 



Experiment 90. Place three or four thicknesses of colored blotting 

 paper on the bottom of a beaker. Thoroughly wet the paper and 

 scatter upon it several radish or other seeds. Cover the beaker with 

 a piece of window glass and put in a warm place. Allow it to stand 

 for several days, being sure to keep the blotting paper moist all 

 the time. When the seeds have sprouted, examine the rootlets, with 

 a magnifying glass or low power microscope, for the root hairs which 



