APPLIED PHYSIOLOGY 



23. Putrefaction. When albumin is kept moist and exposed to 

 the warm air it decays or putrefies, becoming soft and finally completely 

 dissolving, and at the same time giving off offensive odors. If the 

 albumin is kept dry it shrivels up and finally becomes a gluelike sub- 

 stance. Pure sugar or fat will not putrefy, although both may become 

 sour, but both often contain a slight amount of albumin, and this may 

 putrefy, giving them a slight taste and odor. 



24. Diffusion. When salt and water are placed in a 

 bag of thin skin and suspended in a dish of water, some 



of the salt and water will pass through 

 the walls of the bag and will mingle 

 with the water in the dish, and, on the 

 other hand, some water will pass into 

 the bag. This will go on until the 

 water in the dish is of the same salt- 

 ness as the water in the bag. The act 

 of passing through a membrane appar- 

 Diffusion at the begin- entry impervious is a form of diffiision. 

 ring of the process. Without pressure albumin will not dif- 

 fuse except in the form, called peptone, 

 which is produced from the others by 

 digestion. Peptone readily diffuses 

 through the thin sides of the blood 

 tubes in the walls of the intestine, and 

 so reaches the blood. 



Diffusion at the end 

 of the process. 



25. Iron-bearing albumin. The nu- 

 cleus of vegetable cells is composed of a form of 

 albumin called nucleo-albumin, which contains 

 iron. There are from thirty to sixty grains of 

 iron in the human body, all of which is united with the albumin, so 

 that the metallic properties of the iron are completely absent. A 

 small amount of this iron-bearing albumin is found in the nucleus of 

 every cell, both vegetable and animal, and seems to be essential to the 

 growth and division of the cell. In an animal this substance gives 

 origin to the substance called hemoglobin, which forms the coloring 



