FUNCTIONS OF LIFE ELEMENTS 6 



o 



ter that biochemistry is very largely the chemistry of carbon 

 compounds; and it is interesting to observe that in the evolu- 

 tion of life each of these biological compounds must have arisen 

 suddenly as a saltation or mutation, there being no continuity 

 between one chemical compound and another. 



Phosphorus is essential in the nucleus of the cell,^ being a 

 large constituent of the intranuclear germ-plasm known as 

 chromatin, which is the seat of heredity. It enters largely 

 into the structure of nerves and brain and also, in the form 

 of phosphates of calcium and magnesium, serves an entirely 

 diverse function as building material for the skeletons of 

 animals. Phosphates are important factors in the maintenance 

 of normal uniformity of reaction in the blood. 



Sulphur, uniting with nitrogen, oxygen, hydrogen, and car- 

 bon, is an essential constituent of the proteins of plants and 

 animals.- It is especially conspicuous in the epidermal protein 

 known as keratin, which by its insolubility mechanically pro- 

 tects the underlying tissues.^ Sulphur is also contained in 

 one of the physiologically important substances of bile.^ Sul- 

 phates are important factors in the protective destruction, in 

 the liver, of poisons of bacterial origin normally produced in 

 and absorbed from the large intestine. 



Potassium is able to separate hydrogen from its union with 

 oxygen in water, and is the most active of the metals, biologi- 

 cally considered, in its positive ionization.-^ Through stimula- 

 tion and inhibition potassium salts play an important part in 

 the regulation of life phenomena, and they are essential to the 

 living tissues of plants and animals, fresh-water and marine 

 plants in particular storing up large quantities in their tissues.^ 



^Op. cit., p. 241. -Op. cit.. p. 242. 



^ Pirsson, Louis V., and Schuchert, Charles, 19 15, p. 434. ■* W. J. Gies. 



* Caesium is more electropositive. — F. W. Clarice. 



* Loeb, Jacques, 1906, p. 94. 



