ANIMAL FOOD. 273 



functions are impeded. The minute vessels of the lungs are re- 

 laxed and easily congested, and the molecular constitution of their 

 tissue is altered ; hence chronic bronchitis is common among those 

 who take much alcohol, while consumption, often unsuspected, but 

 of a most fatal form, carries off hard drinkers in the prime of life. 

 Other organic changes also take place ; the crystaline lens and retina 

 of the eye are injured and the sight is impaired, an excess of salts is 

 produced in the urine, and gravel and stone are deposited; 

 indeed, there is not an organ that is unaffected. The brain and 

 spinal cord and the whole nervous system suffer, giving rise to" 

 serious derangements which manifest themselves in the worst forms 

 of nervous disease, such as loss of memory and speech, epilepsy, 

 paralysis or insanity. And these derangements, it should be re- 

 membered, are more or less transmitted to degenerate offspring. 

 The moral effects are too well known to need description. 



"Water is indispensable as a component part of food, for it facil- 

 itates the chemical changes which take place in the food. 



The other inorganic principles which are necessary to a healthy 

 condition of the body are compounds of lime, potash, magnesia, soda 

 and iron, together with phosphoric acid, carbonic acid, chlorine and 

 sulphuric acid. Lime and phosphoric acid are of most importance. 



Requirements Vary The amount of food required varies 

 with different individuals; very much depends on age, sex, climate, 

 season of the year, physical and mental exertion. All vital proces- 

 ses, including the assimilation of food, are most rapid in early 

 life and least rapid in old age. In childhood and youth there is 

 also the necessity for making provision for the growth of all parts 

 of the body, as well as the rapid discharge of functions. Man re- 

 quires more nitrogenous food than woman. The vital processes are 

 also most active in spring, least so at the end of summer; more 

 energetic in cold climates than in hot, in highlands than in valleys. 

 Exertion always stimulates these processes. 



ANIMAL FOOD. 



The structure of animal food is identical with that of the 

 human body ; hence nothing is required in addition to it in order to 

 maintain life. Its chief characteristic is that it contains a large 

 proportion of nitrogenous material; but with it there is usually 

 mingled, either naturally or artificially, so much fat or other non- 

 nitrogenous material that it is adapted both for the formation of tissue 

 and for the production of heat and other force. Undue importance 

 is given by some persons to animal food, as if that alone really 

 nourished the system and supplied what is required for work and 

 recovery of strength. No doubt it appeases hunger more thorough- 

 ly than vegetable diet, and satisfies longer because it is digested in 

 <he stomach and that organ gives signs of repletion and retains this 



