CHAPTER VIII. 



PEACTICAL INFERENCES. 



Objects for which plants are cultivated, and the means of promoting them. 

 Plants cultivated for their roots for their foliage for their fibre 

 for their seeds. Farming operations as aids to propitious climatal 

 influences and as counteracting the evil effects of injurious ones. 

 Drainage. Tillage. Manures. Change and variety of cropping. 

 Rotation. Improvement of cultivated plants. Selection. Change of 

 seed. Cross breeding. 



HAVING in the preceding chapters given an outline of 

 the life-history of the plant, the machinery by which it is 

 carried on, the manner in which that machinery fulfils its 

 purpose, and the contest and competition in which living 

 plants are always engaged, it may he well to indicate some 

 of the points in which the history so outlined affects the 

 practice of agriculture. Of course, were science perfect, 

 which it is very far from being, and were practice uniformly 

 intelligent and uninfluenced by mere routine or accidental 

 circumstances, it would be found that no single detail of 

 the plant's history was unimportant to the cultivator. As 

 it is, owing to deficient knowledge on both sides, much of 

 what the student learns in the laboratory has no applica- 

 tion in the field, and much of what the farmer does on the 

 land is without significance to the student. 



It is the object of the series of Handbooks of which 

 this is one, to remedy this state of things, and to bring the 



