INTROD.] OF ORGANIZED BODIES. 9 



lias succeeded in the synthesis of any of the true proximate prin- 

 ciples ; and, indeed, it is very questionable whether any of those 

 products of a vital chemistry will ever be produced elsewhere, than 

 in the living organism. The formation of urea, a secondary or- 

 ganic compound, has been effected by Wohler from the cyanate of 

 ammonia, by depriving it of a little ammonia through the action of 

 heat. And it must be admitted, as no unimportant step in the 

 synthesis of organic compounds, that nitrogen gas has been found 

 to unite with charcoal, under the influence of carbonate of potassa 

 at a red heat. The cyanide of potassium, which is thus formed, 

 yields ammonia, when decomposed by water; so that cyanogen, 

 and, through cyanogen, ammonia, can be primarily derived from 

 their respective elements contained in the inorganic world.* Allan- 

 toin, an analogous compound to urea, and formic acid, have like- 

 wise been artificially produced. 



We proceed from this review of the chemical constitution of 

 organic and inorganic substances, to compare them together in 

 other respects. 



In examining an organic substance which is organised, i. e. so 

 constructed as to form part of a living organism, we find it to 

 possess very distinctive characters. It generally contains water in 

 considerable proportion ; its form is more or less rounded and free 

 from angularity, and it is never crystallized. When considerable 

 hardness or density is required, the quantity of water is small, and 

 an inorganic material is combined with the organic matter; as, in 

 bones, phosphate of lime with the gelatine of the bone, or, in 

 plants, silex with their epidermic tissues. 



An organized body is composed of parts, distinct from each other 

 in structure and function, and it may be subdivided into a series of 

 textures, each differing from the others in physical and vital proper- 

 ties. The existence of a great variety of textures, in an animal, 

 is an indication of a high degree of organiza- p . l 



tion. Among the lowest organized creatures 

 there is much uniformity of structure, although 

 variety of parts or organs. Still these creatures 

 by their actions shew that materials of dif- 

 ferent properties must exist throughout their 

 bodies. 



The simplest and most elementary organic 

 form, with which we are acquainted, is that of Primary organic ceii, she w- 



* inp the cell-membrane, the 



a cell (Fig. 1), containing another within it nucleus, and the nucieoiu 3 . 

 (nucleus), which again contains a granular body (nucleolus}. 

 * Graham's Chemistry, p. 709. 



