CHAPTER XII. 



THE STEM AND BRANCHES. 



You may have observed that so far I have told 

 you a good deal about leaves and roots, flowers 

 and seeds, but little or nothing about the nature 

 of the stems and branches that bear them. I 

 have done this on purpose; for my object has 

 been to give you as much information at a time 

 as you could then and there understand, build- 

 ing up by degrees your conception of plant 

 economy. Now, leaves and flowers are, so to 

 speak, the units of the plant-colony, while stem 

 and branches are the community as a whole and 

 the mode of its organisation. You must know 

 something about the component parts before 

 you can get to understand the whole built up 

 of them ; you must have seen the individual 

 citizens themselves before you can comprehend 

 the city or nation composed by their union. 



The stem, then, is the part of the plant-colony 

 which does not consist of individual leaves, 

 either digestive or floral, but which binds them 

 all together, raises them visibly to the air, and 

 supplies them with water, nitrogenous matter, 

 and the results of previous assimilation else- 

 where. The stem and branches are common 

 property, as it were ; they belong to the com- 

 munity : they represent the scaffolding, the 

 framework, the canals, the roads, the streets, 

 the sewers, of the compound plant-colony. 



How did stems begin to exist at all ? The 



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