CHAPTER IX 



THE ORGANIZATION OF THE INDIVIDUAL 

 PLANT 



In our study of the problems presented by the individual organism we 

 have thus far been concerned with the animal type of organization, as 

 exemplified by man. We have looked at the structure and functioning 

 of the human body in some detail, seeking to learn what its problems of 

 maintenance are and how they are met. Animals, however, are only one 

 of the two great divisions of life; it is now time for us to examine the 

 very different scheme of individual organization that has been developed 

 among plants. 



All the higher forms of life, including those organisms most familiar 

 to us, are either animals or plants. This fundamental dichotomy among 

 living things extends far down the scale of organization. Not until we 

 reach certain of the lowly unicellular forms of life does the distinction 

 between plant and animal become obscure — and this in spite of the 

 tremendous diversity in size, form, and mode of life exhibited by the 

 members of the two groups. In what, then, does the difference consist? 

 What fundamental characteristic makes one organism an animal, another 

 a plant? In final analysis, if we ignore for the moment all superficial 

 differences and all exceptional cases, it comes down to this — that animals 

 capture their food ready made, whereas plants manufacture their food 

 from simple chemical substances. The most important structural and 

 functional differences between plants and animals are attributable to 

 the unlike requirements of their methods of nutrition. 



We shall best be able to comprehend the way in which the individual 

 plant is built and functions by analyzing some representative plant type 

 in detail, just as we di4 the human body. For this purpose, we shall 

 choose not some single species of plant but a group of the flowering plants 

 called the dicotyledons. We are interested in all the details of the human 

 body because they are a part of ourselves. We are not so concerned with 

 the minor features of individual plant species; by treating plants as a 

 group we can select the best examples or generalize for all plants and thus 

 obtain a comprehensive picture of plant structure and functioning. 



The dicotyledons are those flowering plants that have two cotyledons 



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