DEFINITIONS AND DESCRIPTIONS. 45 



fruit or branches ; or when separated from the stalk, of produc- 

 ing a plant, not only of the same species, but of the same va- 

 riety ; -while seeds produce similar species, but not the same 

 varieties. 



7. Eye is a term applied to vital points on bulbous roots, as 

 the potatoe, (Fig. 6, a.) These {)oints are also found on the stem, 

 (Fig. 7, rf,)and are similar to the germ, or vital pouit of the seed. 

 Tliey are in fact the true buds. 



8. Chemical transformation is a term applied to the changes 

 which tcike place in compound bodies, when subjected to the 

 influence of other substances. If the change consists simply in 

 the new arrangement of tlje atoms of the conijjound, the change is 

 called catalytic ; but when the change takes place in the organs of 

 plants, and consists in the body's yielding one ingredient, and 

 forming by its remaining elen^ents, or by elements obtained from 

 the acting body, a new compound ready to pass through other 

 similar changes, then it is called properly a transformation ; and 

 when a series of changes are thus produced upon water, or any 

 other substance, the body is said to pass through chemical trans- 

 formations. 



"An organic chemical transformation is the separation of the 

 elements of one, or of several combinations, and their reunion 

 into two or several others, which contain the same number of 

 elements, either grouped in another manner, or in different pro- 

 portions." — Liehig. 



The catalytic force acts by mere presence. The combination 

 of two bodies in contact with other compounds, causes the latter 

 to enter into a similar state. The process of fermentation will 

 serve to illustrate the nature of this force. A small quantity of 

 matter, in a state of fermentation, causes an indefinite quantity 

 to enter into a similar state, as when yeast is introduced into 

 dough. 



9. A simple substance is one which has never been resolved 

 into two kinds of matter, such as charcoal, silver, gold, iron, etc. 

 The number of simple substances is fifty-five ; and they are re- 

 presented by letters or symbols; thus, O stands for Oxygen, 

 H. for Hydrogen, C for Carbon, and N for Nitrogen. The quan- 

 tity in which any body combines, is expressed in numbers, hy- 

 di'ogen being taken for unity. Only fourteen simple bodies are 

 found in vegetables, of which the following are the names, 

 equivalents and symbols. Hydrogen, symbol H, equivalent 

 1 ; Oxygen, Symb. O, Equiv. 8, and Nitrogen, N — 14, which, in 



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