The Chemical Constituerds of the Organism. 7 



All proteids contain carbon, hydrogen, oxygen, nitrogen, 

 and sulphur. 



Carbon - - 50 to i>i> per cent. 



Hydrogen - - GG to l-'\ „ 

 Oxygen 1'.' to 24 ,, 



Nitrogen - -15 to l'J „ 



Sulphur - - '3 to 2-4 ., 



In the animal body proteids undergo a breaking up, the 

 complex body is resolved into simpler bodies, resulting in 

 the production of such substances as leucin and tyrosin, and 

 from these the proteids are eliminated as carbonic acid, 

 urea, and water. The substances resulting from this breaking 

 up are known as decomposition products. 



Some albumins are soluble in water, others in saline solu- 

 tion strong or weak, and in this way it has been possible to 

 classify the true proteids. 



Albumins are soluble in water, in weak salt solution, and 

 coagulated by heat ; belonging to this class are serum, egg, 

 muscle, and vegetable albumin. 



Globulins (which are also true albumins or proteids) are 

 insoluble in water, but soluble in dilute solution of common 

 salt and precipitated by heat. In this class are found the 

 globulin and fibrinogen of the blood plasma, also that found 

 in the crystalline lens, the vitellin of eggs, etc. 



Fibrin is a solid albuminous substance produced by a fer- 

 ment in blood, chyle, and lymph ; it is insoluble in water, 

 but soluble in weak saline solution. 



The Derived Albumins are obtained by the action of acids 

 or alkalies on true albumins. These bodies are insoluble in 

 water, but are soluble in dilute acid and alkalies, and in 

 weak salt solution. They are not coagulated by boiling as 

 the true proteids are. To this class belong acid albumin 

 or syntonin, alkali albumin, and the albumin of milk, 

 caseinogen. 



If any of the above proteid bodies be acted upon by the 

 gastric or pancreatic secretions, they undergo a change into 

 a substance known as peptone ; but before reaching the 

 peptone stage they pass through an intermediate one known 



