FHYSIOLOG Y. 1 5 



When an organic substance, which is so constructed as to form 

 part of a living organism, is examined, it is found to possess some 

 very distinctive characters. It contains water in considerable pro- 

 portion ; its form is more or less rounded, and free from angularity, 

 and it is never crystallized. When it is necessary that it should 

 possess considerable hardness, the amount of water is small, and an 

 inorganic material is combined with the organic matter, as the phos- 

 phate of lime with gelatine in bones, or the silex with the epidermic 

 tissues, in plants. 



An organized body is composed of parts which differ from each 

 other in structure and function ; it may be subdivided into a series 

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

 perties. When a great variety of textures exist in an animal, it is 

 an indication of a high degree of organization. 



The simplest and most elementary organic form, is that of a cell 

 containing another within it, [nucleus,) which again contains a gr^- 

 nularbody,(?zZ('c/eoZw5.)(Fig. 1.) This appears 

 to be the primary form which organic matter Fig. 1. 



takes as it passes from the condition of a proxi- 

 mate principle to that ofan organized structure. 



In some animals and vegetables, the whole 

 body is composed of cells of this kind, and 

 in the development of the embryo, all the tis- 

 sues, however dissimilar, are composed of 

 cells which are afterwards metamorphosed 

 into- the various structures that make up the 

 perfect being. 



Every organized body has a definite form and size ; it has also 

 its origin from parents, and has an allotted time to live ; and after 

 death it passes by decomposition into the simpler combinations of the 

 inorganic elements. 



Organized bodies grow by materials which are deposited within, 

 and carried to the different parts of the structure by a vital process. 

 They have also the power of repairing parts lost either by injury or 

 disease. Parts that have been removed, may be replaced by a pro- 

 cess of growth in the plant or animal, and this process is the more 

 energetic in proportion as the structure of the organized body is 

 more simple. The part that has been separated, however, in the 

 higher orders, perishes ; but in the lower orders, it often happens 

 that the severed portion becomes a new and independent being, as is 

 the case with the hydra, in the animal kingdom, and with certain 

 members of the vegetable kingdom, cuttings of which will often pro- 

 duce a similar plant to that from which it was stricken. 



Organized bodies have the power of appropriating or assimilating 

 to their own textures, other substances, both organic and inorganic. 

 By virtue of this process, plants and animals are continually adding 



