*f HE STORY OP THE LUNGS, SKIN AND KIDNEYS 9? 



temperature. The urine consists in 1000 parts, of 

 about 958 parts of water and 42 parts of solids, the 

 latter consisting of urea, uric acid, minerals and 

 other substances, whilst a certain amount of carbonic 

 acid gas has also to be reckoned with as being 

 contained in the urine. The special feature we have 

 to remember in connection with the functions of the 

 kidneys relate to the urea and the uric acid. Both 

 substances represent what we may term the break- 

 down of the nitrogenous foods consumed and utilised 

 by the body. The uric acid, in the opinion of many 

 physiologists, represents a stage in advance of that 

 which results in the production of urea. As an 

 excess of uric acid in the body is the cause of gout, 

 that disease may be presumed to arise from some 

 condition or other which prevents the work of the 

 kidney being carried on to its normal end. 



A BODILY BALANCE SHEET. It is now possible to 

 summarise in the form of a bodily balance sheet the 

 general income and expenditure of the living body, 

 the details of which have hitherto formed the subject 

 of our studies. In this fashion we may gain a 

 summarised idea of the manner in which the 

 business of life is conducted, and we may also be 

 prepared to discover that in respect of economical 

 working, nature presents a highly typical example of 

 the wise and orderly ruling in her conduct of the 

 human household. The total income of a human 

 being is derived from three sources, namely, the solid 

 food he consumes, the water or other fluids he drinks, 

 and the oxygen of the air he inhales. The expendi- 

 ture of his body is represented by the waste materials 

 which have resulted from the work his body performs. 

 The income of an adult man doing an ordinary amount 

 of work per day may be calculated as nearly as possible 



