xxv.] BOTANY. 99 



mon observer, as those of the carrot and parsnip, which 

 are two genera of one order ; at other times they depend 

 on characters of flower and fruit that are not recognized 

 without botanical knowledge, as those of the butter- 

 cup and larkspur, which, though so unlike, are members 

 of one order. 



Classes are groups of a still higher value, as those 

 of monocotyledon and dicotyledon. All classes are 

 grouped under the two sub-kingdoms of flowering 

 and flowerless plants which constitute the vegetable 

 kingdom. 



149. Individuality. Plants, especially perennial 

 ones, are often regarded as composite beings, or aggre- 

 gates of individuals, because their buds may be 

 detached and become separate individuals; because 

 many parts annually die, and are replaced by similar 

 parts ; and because much of the substance of a tree 

 or bush dies and remains as dead matter throughout 

 the future life of the plant, forming a support as it 

 were for the fresh buds developed from the living 

 tissues that surround it. But whereas it is only of 

 some plants that the buds are capable of becoming 

 separate individuals, there are others of which single 

 cells are capable of playing the same part ; so that if 

 the answer to the question of " What is an individual 

 plant?" is to depend on this power of its parts to 

 maintain a separate existence, it is a purely speculative 

 one, and we are reduced to accept the only alternative 

 of regarding each specimen as an individual, so long 

 as if remains an organic whole. 



150. Origin of Varieties. The result of cross- 

 fertilization (Par. 119) is that the qualities of two 

 distinct individuals are combined in the embryo and 



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