188 



COMMERCIAL POULTRY RAISING 



is the foundation or base of all living tissue — the substance 

 through which life is manifested. The muscles, skin, tendons, 

 brain, feathers, blood and internal organs are composed chiefly 

 of protein. The white of the egg when dry is almost all protein, 

 while the dried yolk is one-third protein. 



-30" 



Fig. 127. — Designs for feed hoppers that are sanitary and non-wastefuL 



Ash, or the mineral substances, such as lime, silicon, mag- 

 nesium and so on, form the incombustible material of the body. 

 In short, ash is that part of the body which is left after the vola- 

 tile and combustible elements are driven off by heat, the heat 

 being created by the fats. Considerable ash enters into the egg, 

 and it is an important element in the structure of bone and 



