Johnston makes everything so plain that I can mighty near see what
he saw when he looked through the microscope."

"I greatly enjoyed my microscopic work," said Percy, "and still more
the work in the chemical laboratory where we finally learned to
analyze soils, to take them apart and see what they contain,--how
much nitrogen how much phosphorus, how much limestone, or how much
soil acidity, which means that limestone is needed. Then I also
enjoyed the work in the pot-culture laboratory, where we learned not
to analyze but to synthesize; that is, to put different materials
together to make a soil. Thus, we would make one soil and put in all
of the essential plant food elements except nitrogen, and another
with only phosphorus lacking, and still another with both nitrogen
and phosphorus present, and all of the other essential elements
provided, except potassium, or magnesium, or iron. These prepared
soils were put in glass jars having a hole in the bottom for
drainage, and then the same kind of seeds were planted in each jar
or pot. Some students planted corn, others oats or wheat or any kind
of farm seeds. I grew rape plants in one series of pots, and I have
a photograph with me which shows very well that all of the plant
food elements are essential.

"You see one pot contained no plant food and one was prepared with
all of the ten essential elements provided. Then the other pots
contained all but one of the necessary soil elements, as indicated
in the photograph."

"Why, I never saw anything like that," said Mrs. Thornton.

"But I have many a time," said her husband, "right here on this old