CHAPTEE I 



LIVING MATTER: ITS CHEMICAL AND PHYSICAL BASIS 



CONTENTS. 1. The cell-theory. 2. Morphology of the cell. 3. Structure of 

 protoplasm. 4. Structure of nucleus. 5. Chemical elements of the cell. 6. Protein 

 basis of living matter. 7. Classification of proteins. 8. Chemical constitution of 

 proteins. 9. Enzymes or ferments. 10. Classification. 11. Other nitrogenous 

 organic substances, fats, carbohydrates or saccharides, inorganic substances. 

 12. Chemical structure of living matter. Bibliography. 



IN Nature no phenomena can be independent of a material sub- 

 stratum : all are the external manifestation of the energies im- 

 manent in matter. Every vital phenomenon that comes under the 

 observation of the physiologist is intimately connected with the 

 living organism, and is the expression of internal causes, i.e. of the 

 different forms of energy inherent within that organism. 



Whoever, then, approaches the threshold of Physiology in order 

 to study the Manifestations of Life, will feel it essential to have 

 some knowledge of the material substratum out of which the 

 living phenomena have been evolved. 



I. Both in plants and animals the material substratum of vital 

 phenomena, the physical basis of life, consists of a substance of 

 highly complicated structure and constitution, soft or gelatinous 

 in consistency, to which Hugo Mohl (1846) gave the name of 

 protoplasm. In living beings this does not appear as a simple 

 mass, without form or boundaries ; but it is divided into minute 

 particles, or separate entities, known as cells. Each cell comes 

 from a pre-existing cell, just as every living being comes from the 

 ovum, which is the primitive cell. The so-called Protista, which 

 are the most primitive form of life (and probably constitute the 

 common stock whence plants and animals have developed) are 

 throughout their whole life represented by a single cell, which 

 assumes various forms and dimensions. In the Metazoa, on the 

 contrary, the primitive cell, or ovum, gives rise to other similar 

 cells, and these to other cells in turn, which are gradually differ- 

 entiated, transformed, and adapted to the several physiological 

 offices which they serve. 



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