PART I. 

 ORGANOGRAPHY. 



GENERAL CONSIDERATIONS. 



The lowest forms of plant life are so simple in their structure 

 that they can hardly be said to possess distinct organs or parts 

 for the performance of different kinds of work. With them, so 

 to speak, the work of vegetable life is performed without imple- 

 ments, in the rudest manner. But as we pass up the scale of 

 vegetable life we find plants growing more and more complex in 

 their structures, the plant body tends more and more to be 

 divided into organs, till at last, when we reach the highest group, 

 the flowering plants, we find it to consist of a variety of parts, 

 each differing from the other in appearance and structure, and 

 each contributing in a somewhat different way to the life of the 

 whole organism. Our study, therefore, of organography will be 

 mainly confined to the organs of the higher plants, where we find 

 them most highly developed. 



In flowering plants we observe two kinds of organs ; first, the 

 vegetative, or those which imbibe, circulate and elaborate food, 

 and contribute to the vegetable life of the plant ; and second, 

 the reproductive, or those whose function it is to reproduce the 

 species. 



The vegetative organs consist of Roots, Stems, Leaves and 

 Hairs. All of these organs occur under numerous modifications. 

 The same plant may bear several different kinds of each of them, 

 some adapted to one use, others, perhaps, to quite a different 

 one, so that what is, morphologically speaking, the same organ, 

 may perform a variety of quite distinct functions. It is not 

 Nature's method to create new organs when new uses are required, 

 but to reshape and modify already existing ones, and fit them 

 for the new requirements. If, for example, it is of advantage to 



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