12 
LABORATORY EXERCISES 
are suggestive but they may be modified or others substituted for 
them if expedient. 
I. Temperature. In three separate boxes of moist sand plant 
seeds of the same kind. Place one box in a cool place (50° F.), one 
in a very warm place (120° F.), and the third in a moderately warm 
place (70° or 80° F.). Be sure that the preparation of the boxes 
and the care given them are the same in all particulars. (To pro¬ 
vide equal moisture in the sand more water will be required for 
the boxes in the warm place than for those in the cool.) Observe 
from day to day. In which case are the best results obtained so 
far as the proportion of seeds germinating and the rapidity of 
germination are concerned? 
II. Moisture. Plant seeds of the same kind in each of three 
dishes of sand. Be sure that all the conditions are the same, 
except that in one case no water shall be added; in another, the 
sand shall be sufficiently wet for water to be evident above the 
surface; and in the third, the sand shall be only moderately moist. 
Observe the results as in Part 1. 
III. Air. Fill two small glass bottles with soaked peas. Cover 
one bottle in such a way that there can be no exchange of the air 
inside with that outside. Leave the other uncovered. Observe 
the results. Explain. 
EXERCISE 13 
TESTS FOR NUTRIENTS 
I. Test for Starch. Place the same amount of water in each of 
two test tubes. To one add a little thin starch paste, and to each, 
a few drops of iodine solution. Note the result. The tubes are 
alike except in one particular. What is it? To what must the 
difference in results be attributed? What, then, is a test for 
starch as shown by this experiment? 
II. Test for Glucose. Add the same amount of water to each 
of two test tubes. To one add glucose. Now add Fehling’s solu- 
