90 BOTANT. 



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 tlie two pots. 



(b) Observe the average daily tempeiature during the time that the 

 hickory-trees are opening tlieir 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 thermnmetcr 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 sliclis and stones. 



(d) Measure in lilse 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 ot the soil at the average depth of the roots. 



(/) Enclose a small plant of Coleus (a common "foliage-plant") 

 and a clover-plant in a tin pail, covering them loosely. Enclose also 

 a thermometer. Set the pail in a tub of ice-water, allowing it to 

 remain for an liour or two. Note the effect upon each plant. Or 

 make the experiment by first growing little plants of wheat and 

 pumpkin or squasli, 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 Palir.), 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. 



{K) 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. 



