116 Principles of Plant Culture. 



after maturity by exposing them to the sun a few days, 

 or by placing them for a like time in a refrigerator 

 containing ice. By these means, the farmers of Ten- 

 nessee grow a second crop of potatoes in the latter part 

 of summer and during autumn. 



Plants under glass usually thrive better after mid- 

 winter than before, and the most favorable time to 

 plant seeds of greenhouse plants is toward the close of 

 the natural rest period. 



179. The Round of Plant Life has now been traced, 

 from the first swelling of the planted seed, through the 

 development of the embryo into the plantlet, the pene- 

 tration of the root into the dark and damp soil cavities, 

 the absorption and conduction of water with its food 

 materials in solution, co-operating with the sunlight 

 and carbonic acid in the mysterious laboratory of the 

 leaf, in building up the plant body into node and inter- 

 node, leaf, bud, branch, flower, fruit and seed; through 

 growth decline, leaf fall and winter sleep, to the re- 

 newed vigor of another springtime. 



In our study of the round of plant life, we have as- 

 sumed the environment to be favorable. But in the 

 practical culture of plants, we are constantly meeting 

 with adverse conditions of environment. Talent for 

 plant culture lies in the ability to discern these adverse 

 conditions by the appearance of the plant, and in know- 

 ing how to correct them. We will, therefore, next con- 

 sider the plant as affected by unfavorable conditions of 

 environment. 



