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BIOLOGY. 



2. Processes. 



1384. The tissues of plants form three formations, 

 which must be similar in their functions, and can only 

 exhibit subordinate differences. The cell-formation is 

 displayed in the cellular tissue, in the bark and root. 

 The vascular formation in the vascular tissue, in the liber 

 and stalk. The tracheal formation in the tracheal tissue, 

 the wood and the leaves. There can accordingly be only 

 three principal functions in the vegetable stem, and of 

 these each will display minor differences. 



A. Cellular Processes. 



a. ROOT-PROCESS ABSORPTION. 



1385. As the root is the cellular organ proper, so in 

 it principally resides the water-process or the commence- 

 ment of chemical elaboration and analysis. Now the 

 chemism in an organic body is called digestion. 



1386. The root is the mouth or pharynx of the plant, 

 and is therefore principally concerned with absorption. 

 Its process is therefore the formation of mucus, or as it 

 were of salivation. The root cannot, however, create 

 mucus, as it was created at the conclusion of the earth- 

 metamorphosis in the sea; it can absorb it or in the 

 highest degree compound it out of the constituent parts. 



1387. The process of the formation of mucus is a pro- 

 cess of putrefaction ; the function of the root consists 

 accordingly in supporting a constant process of putre- 

 faction. The soil in which the root stands must contain 

 substances susceptible of, and the conditions necessary to, 

 putrefaction. These substances are organic matters and 

 water ; the conditions heat and access of air. Such a 

 soil is called humus or mould. In a pure, dry earth, no 

 root can thrive. 



1388. Carbon, from its being the earthy body, is the 

 principal one in the formation of mucus, and the basis 

 also of the vegetable bodies. A root can develop itself, 

 if it stand only in a soil such as the calcareous, which 



