90 BOTANY. 
as well in darkness as in the light, behaving in this respect 
like parasites and saprophytes. 
Practical Studies.—(a) Plant a few seeds of radish, barley, wheat, 
and Indian corn in each of two flower-pots, and place one of the pots 
in a cool cellar and the other in a warm room. Note differences in 
growth in the plants in each pot, and also compare growth of similar 
plants in the two pots. 
(b) Observe the average daily temperature during the time that the 
hickory-trees are opening their buds in the spring. Compare this 
with the average temperature during the time of most vigorous de- 
velopment of the leaves and twigs, and also during the time of the 
development of the fruit. 
(c) With a thermometer measure the temperature of the water of 
ponds and ditches when the earliest vegetation appears in the spring. 
This consists for the most part of diatoms which form a brownish 
scum on the water, or a brown coat on sticks and stones. 
(@) Measure in like manner the temperature of cold springs in which 
vegetation is found. 
(e) When Indian corn is producing its flowers (tassels and silk), ob- 
serve the average temperature of the air and compare it with the 
temperature of the soil at the average depth of the roots. 
(f) Enclose a small plant of Coleus (a common ‘‘ foliage-plant”) 
and a clover-plant in a tin pail, covering them loosely. Enclose also 
athermometer. Set the pail in a tub of ice-water, allowing it to 
remain for an hour or two. Note the effect upon each plant. Or 
make the experiment by first growing little plants of wheat and 
pumpkin or squash, and using these. The wheat will survive; the 
pumpkin or squash will not. 
Now make an experiment substituting hot water, and using a 
spring plant (as hepatica or anemone) and a summer plant (as Indian 
corn). Raise the temperature to 40° Cent. (104 Fahr.), and then in- 
crease the heat very slowly beyond this point. Notice effect upon 
each plant. 
(g) In the autumn notice that some plants are killed by frosts which 
leave others unharmed. 
(h) Thaw out two frozen apples, one in warm water rapidly, and 
the other in ice-water slowly. The first will be more injured, the 
second less. 
(i) Look for moulds and other fungi in dark cellars, as examples 
of saprophytic plants which have grown without the direct aid of 
light. 
