340 Missouri Agricultural Report. 



V)i the plant. These are usually tougher and more resistant than the 

 ordinary cell walls, and the cellulose in the skins is the most resistant 

 of any we have to deal with in cooking. The main functions of the 

 skin cellulose are to hold in the moisture the vegetable contains and to 

 protect it from the action of molds and bacteria. Without the dense 

 coats of skin cellulose potatoes and apples could be kept no longer 

 than some of the more perishable fruits, as strawberries. We turn this 

 property of skins to good account when we cook beets or potatoes with- 

 out paring them in order to lose none of their nutrient materials. In 

 the beet we can measure roughly the loss of nutrients by the correspond- 

 ing loss of color, and we know this is least when the skin is unbroken 

 and the leaves cut off a long way from the beet, and, better still, the 

 passages in the stems are allowed to close by drying and shriveling. 



Cooking has little or no effect on the cellulose forming the walls 

 of the cells, but there is a modified form of cellulose holding these to- 

 gether which is greatly softened by cooking in boiling water. If we 

 examine a little, well mashed potato under the microscope, we see that 

 very few of the cell walls are broken, but that they have separated 

 from each other because of the softening of the substance which held 

 them together when raw. If we subject a little of the same material 

 to the action of saliva for a few minutes and again examine, we find 

 that no starch remains, showing that even though the cell walls of the 

 potato have not been broken by the cooking, nor even by the mashing 

 after cooking, these walls, seemingly, have not interferred with the di- 

 gestion of the cell contents so long as the digestive fluids come in con- 

 tact with the cell. One important object of cooking vegetables, then, is 

 to soften the intercellular substance so that after mastication the con- 

 tents of each cell may be exposed to the action of the digestive fluids. 



The cells contain, besides a large percentage of water, the nutrients, 

 starch, sugar, proteid, fat, and the mineral matter. Of these, starch 

 is the only one made more digestible by cooking. The same high moist 

 heat that softens the cellulose also changes the raw starch into a digesti- 

 ble paste. 



The mineral salts are, perhaps, the most important of these nutri- 

 ents, because vegetables form the greatest source of these salts, which are 

 so essential to the good health and the proper functioning of our body 

 cells and organs. Though never required in large quantities, as compared 

 with the carbohydrates or proteins, life is not possible without them. 

 It has been found by experiments that deprived of the mineral salts and 

 eating other food, and drinking water, man could live only a few days, 

 from twelve to fifteen, perhaps, though, with water alone, and deprived 

 of all other food he can live for from forty to sixty days. One of our 



