THE FRONTIERS OF MEDICINE 



solutions may be greatly increased in amount, or other 

 substances may be excreted which are never found in the 

 urine under normal conditions. Thus careful and complete 

 chemical analysis of the urine leads to a better understand- 

 ing of what is going on in the body. Quite logically, when 

 any unusual substance is found in too great an amount, the 

 tendency is for the physician to advise the patient to eat 

 less of the substance which may give rise to the unusual 

 material. By this means pathological conditions sometimes 

 may be brought under control. 



In an earlier day, the only examination made of the urine 

 was to look at it in the light and to judge whatever might 

 be judged with the unaided five senses. Gradually it has 

 been realized that these excretions are an index of the body 

 chemistry. The specimen may now be submitted to dozens, 

 if not hundreds, of tests, the answers to each of which 

 yield important knowledge. But here, again, only a begin- 

 ning has been made; a vast amount of additional knowledge 

 will be necessary before the whole truth is known. 



Wafer. A good subject for a debating society with some 

 knowledge of science would be the question as to whether 

 water or oxygen is more important for the human body. 

 Without oxygen one dies promptly, and without water, 

 more slowly. Death from lack of oxygen is sudden and 

 relatively painless; death from lack of water may be long 

 and involve terrific upsets in the machinery of the human 

 body. 



Water carries materials into the body and out of it. As 

 part of the blood it is concerned with interchange of mate- 

 rials within the body. Through its function of passing 

 through membranes, it makes possible the continuous 

 transfer of material from one cell to another and from one 

 organ to another. 



By the evaporation of water from the surface of the body 

 the temperature of the human being is carefully regulated. 



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