FOODS. 139 



ing the solidity of the bones and teeth, replacing the amount metab- 

 olized daily! inasmuch as me metabolism of these two tissues is 

 slight, there is not much need in the adult for lime as an article of 

 food. In young animals lime is essential to the solidification and 

 development of bone. When deprived of it, the skeleton undergoes 

 a defective development similar to the pathologic condition known 

 as rickets^ Lime is present in milk to the extent of 0.15 per cent., as 

 well as in eggs and peas in relatively large quantities, fe 



Iron is contained in both animal and vegetable foods, not, how- 

 everfirTthe form of inorganic iron, nor in the form of an organic salt, 

 but as a compound with nuclein, ; thus forming an integral part of the 

 proteid molecule. After absorption the iron is utilized in the forma- 

 tion of the coloring-matter of the blood-corpuscles hemoglobin.V 

 The organic compounds of iron and the nucleins have been termed 

 hematogens. The amount of iron ingested has been estimated at 

 from 10 to 90 milligrams, the larger part of which is eliminated in 

 the feces. The relatively small part eliminated by the kidneys and 

 liver is usually taken as the amount metabolized, though it is probable 

 that this is not wholly true, as there is evidence that iron can be re- 

 tained in the body and utilized again in the formation of new hemo- 

 globin. Contrary to what might be expected, milk contains but a 

 very small quantity of iron, not more than 3 or 4 milligrams in 1000 

 grams (human milk) an amount insufficient for the development of 

 the necessary hemoglobin. This is compensated for, however, by 

 the accumulation of iron in the liver during intrauterine life. Ac- 

 cording to Bunge, the liver of a newly born rabbit contains as much 

 as 1 8. 2 milligrams per 100 grams of body- weight, while at the end 

 of twenty-four days it only contains 3.2 milligrams per 100 grams of 

 body-weight. 



Ve^etable_acids increase the secretions of_the alnrientary canal, and 

 are apt, in large amounts, to produce flatulence and diarrhea. After 

 entering into combination with bases to form salts, they stimulate the 

 action of the kidneys and promote a greater elimination of all the 

 urinary constituents. In some unknown way they influence nutrition ; 

 when deprived of these acids, the individual becomes scorbutic. 



The accessory foods, coffee, tea, and cocoa, when taken in 

 moderation have a stimulating influence on the nervous system, as 

 shown by the removal of both mental and physical fatigue, by an 

 increased capacity for sustained mental work, by the persistent wake- 

 fulness among those unaccustomed to their usej Coffee more especially 

 increases the frequency and force of the heart-beat, raises the arterial 

 pressure, and hastens the general blood- flow/f It has no jpfluaice 

 either in the way of increasing or decreasing proteid metarjorismyy 



Tea frequently acts as an astringent on the alimentary canal on 

 account of the tannin which passes into the water when the infusion 



