FOOD AND DIETARIES 



109 



Vitamines. Experiments with mice and guinea pigs, as well as 

 with human beings and other animals, have shown that the various 

 proteins in the materials used as food do not all behave alike in rela- 

 tion to maintaining body weight or in relation to growth. The chemi- 

 cal analysis of proteins that behave in these different ways shows 

 that certain groups of elements contained in some proteins are abso- 

 lutely necessary for growth, while other amino adds are sufficient to 



FIG. 35. The importance of suitable diet 



The child in these pictures was suffering from defective nutrition. In the first picture 



it weighed 14 pounds 4 ounces. The second picture was taken eleven weeks later, 



after expert treatment, when the child weighed 17 pounds 15 ounces. Photographs by 



Dr. Henry Dwight Chapin, at the Speedwell Society 



maintain weight, although they cannot be used in growth. It has also 

 been found that there must be present in some of the food materials 

 certain substances (aside from the well-known fats, carbohydrates, and 

 proteins) that have a direct influence upon growth. These various 

 unknown substances have been roughly grouped together under the 

 name vitamines, which suggests that they are compounds somehow 

 related to " life." But there are probably many very different sub- 

 stances which are related to life ; and they are necessary for 

 protoplasm activity in several different ways. Pellagra and other 

 diseased states are due to the use of food lacking in vitamines. 



