INTEODUCTION. 6 



mately die. But the inorganic body maj- continue to exist until some 

 disrupting force separates the inorganic elements of which it is com- 

 posed, and enables them to form new combinations ; but so long as 

 uninfluenced by such an agency it may remain unchanged for an indefi- 

 nite period. 



4. Size. — Organized bodies have a definite limit to which they may 

 attain, varying, however, among individuals of the same species. And 

 when they exceed the average size of the species it is not by the 

 increased size of the individual, but by the continued production of new 

 individuals or a repletion of parts already existing. The unorganized 

 bod}', on the other hand, is as indeterminate in size as in duration, con- 

 tinuing to grow so long as fresh particles are brought together. 



5. Chemical Constitution. — Of the sixty -five simple elements found 

 in nature but about twenty enter into the composition of organized bodies, 

 and of these but four are to be regarded as essential, viz., C.O.H.N., 

 of which at least two are found in every organic compound. The remain- 

 ing elements are called incidental. Unorganized bodies may be simple in 

 their composition, or binary, ternary, quaternarj-, or higher; but binary 

 is the most usual combination. 



The molecular constitution of the organic body is also different 

 from the inorganic in being much more complex, both in the number of 

 elements which it contains and the number of atoms, or combining 

 equivalents of those atoms, which exist in a combining equivalent of 

 the compound. Thus, albumen, which forms an important constituent 

 of nearly all organized bodies, may be represented as C 2M H 3M N 65 0,5S 3 

 (Schiitzenberger), while ammonium carbonate, an inorganic compound 

 containing the same elements, with the exception of sulphur, may be 

 written as follows: (XH 4 ) 2 C0 8 +H 2 0. 



From the large number of elements which enter into the composition 

 of organic bodies, and the large number of atoms constituting an organic 

 molecule, arises the great tendency to decomposition by which they are 

 characterized; for, "the greater the number of atoms of an element 

 which enters into the formation of a molecule of a compound, the less 

 is the stability of that compound." 



Inorganic compounds are therefore stable ; organic bodies, unstable. 



It was formerly supposed that organic compounds could only be 

 formed under the influence of vitality, and that they could be decom- 

 posed by the chemist, but not recomposed. But this has been shown to 

 be an error, some of the organic acids, alcohols, organic coloring matters, 

 and some of the secondary organic components, such as uric acid and 

 urea, having been synthetically prepared by the chemist. It is thought, 

 therefore, not to be impossible that some of the higher organic com- 

 pounds, such as albumen, may ultimately be also made in the same 



