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CHAPTER V. 



OF THE BARK. 



Under the Cellular Integument we find the Bark, 

 consisting of but one layer in plants or branches only 

 one year old, and often not distinguishable from the 

 wood. In the older branches and trunks of trees, it 

 consists of as many layers as they are years old, the 

 innermost being called the liber ; and it is in this layer 

 only that the essential vital functions are carried on for 

 tlie time being, after which it is pushed outwards with 

 tiie Cellular Integument, and becomes like that a life- 

 less crust. These older layers, however, are for some 

 time reservoirs of the peculiar secreted juices of the 

 plant, which perhaps they may help to perfect. 



In some roots the bark, though only of annual du- 

 ration, is very thick ; as in the Carrot, the red part of 

 which is all bark. In the Parsnep, though not di- 

 stinctly coloured, it is no less evident. In the Turnip 

 it is much thinner, though equally distinct from the 

 wood or body of the root. 



The Bark contains a great number of woody fibres, 

 running for the most part longitudinally, which give it 

 tenacity, and in which it differs very essentially from 

 the parts already described. These woody fibres when 

 separated by maceration exhibit in general a kind of 



