Protein — Albuminoids 57 



These proteids are familiar objects on the farm, and 

 their properties are matters of common observation. 

 When the farmer's boy secures the tenacious cud of 

 gum from the fresh wheat gluten, or when the house- 

 wife watches the strings of coagulated albumin sepa- 

 rate from the cold water extract of fresh lean beef that 

 is brought to the boiling point, or observes the white 

 of an egg harden into a tough, white mass as it is 

 dropped into boiling water ; when we observe the 

 stiffening of the muscular tissue of the slaughtered 

 animal or the rapid formation of strings of fibrin in 

 the cooling blood; — in all these instances there are 

 manifested certain chemical or physical properties which 

 pertain to these most important and useful com- 

 pounds. 



The alhuminokls.—Oi all the nitrogen compounds, 

 these exercise the most general and prominent func- 

 tions in plant and animal life. They not only make up 

 a large part of the protein of feeding stuffs, but their 

 office in the nutrition of animals is definitely under- 

 stood to be of the most important kind. 



As has been indicated, the albuminoids are regarded 

 as divisible into groups, the individuals of each group 

 having certain distinguishing common properties. The 

 two subdivisions whose members are most common 

 and widely distributed are the albumins and globulins. 

 Among these and their derivatives and compounds we 

 find albumin, mj'osin, fibrinogen, albuminates, pro- 

 teoses, peptones, casein and nuclein, — a formidable lot 

 of names whose use seems necessary to a statement of 

 the facts we wish to discuss. It is hoped that the 



