CHAPTER V. 

 DEVELOPMENT. 



Progressive changes during growth. Morphological, physical, and phy- 

 siological. Influence of inheritance. Variation. Selection. Re- 

 serve-materials : their formation and transport. Germination. 

 Maturation. Ripening of fruits and seeds. 



Development as here understood includes those pro- 

 gressive changes of form and appearance which accom- 

 pany the growth of a plant from an infantile to an adult 

 state. It forms no part of our present plan to pursue 

 this part of the subject here, as any elementary text-book 

 contains sufficient details as to the progressive organiza- 

 tion of flowering plants. Growth considered separately 

 results in increase of bulk only, but development includes 

 the whole cycle of changes which convert an atom of 

 homogeneous protoplasm into a tree laden with fruit or 

 into a wheat plant heavy with golden ears. A mangel or 

 a turnip which, under favorable circumstances, gets big- 

 ger and bigger, may be said to grow. It increases in size 

 and weight, but neither its outward appearance nor its 

 internal construction is otherwise much affected. The 

 giant mangels exhibited at root shows illustrate growth 

 rather than development. They are very big, but their 

 nutritive power is by no means in proportion to their 

 size, as the quantity of nutritive matter developed is 

 small indeed as compared with the great quantity of 

 water they contain. Growth, in fact, is but the prepara- 

 tory stage, during which material and machinery are 

 acquired, to be turned to subsequent use in the consoli- 

 dation of the stem, the construction of flower and seed, 

 the formation and storage of reserve food-materials, of 

 starch, of oil, of the various secretions, such as the 

 caoutchouc, the alkaloids, as quinine, morphia, and many 

 others. 



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