INORGANIC FOODS. 363 



The serum now contains a substance which did not occur in it previously, 

 or at any rate not to the same extent as now; namely, the newly formed 

 sodium salt. It is the duty of the kidneys, as we shall see later, to keep 

 guard over the serum and to regulate its chemical composition. They 

 eliminate every constituent which under normal conditions is foreign to 

 it, and take away any excess of compounds which belong there. In the 

 above case the kidneys eliminate the newly formed sodium salt together 

 with the potassium salt. This process, therefore, results in the serum 

 being deprived of sodium chloride. 



Bunge succeeded in testing this theory experimentally. He himself took 

 18 grams of K 2 O as phosphate and citrate in three doses during the course 

 of the day, and showed that as a result his body lost 6 grams of sodium 

 chloride. This does not constitute an abnormal amount of potash salts. 

 A man fed largely on potatoes will easily take 40 grams of K 2 O into his 

 system during the day. The loss of sodium chloride is by no means 

 restricted to the blood. There is a constant exchange of material between 

 it and the cells. After what we have seen with regard to the effect of the 

 ions, we can easily understand the possibility that a diminution in the 

 amount of sodium contained in the cells, which is in no way replaceable 

 by potassium ions, may lead to serious disturbances. The organism, at 

 all events, will attempt as soon as possible to restore the disturbed equili- 

 brium. 



Bunge, to support his views, cited numerous facts. He showed, for 

 example, that in France the country folk consume three times as much 

 salt per capita as those who dwell in cities. Now it is a fact that in the 

 country much larger quantities of vegetables are eaten than in the city, 

 where the diet consists largely of meat. A further support of the assump- 

 tion that the vegetables rich in potassium were the cause of the increased 

 consumption of salt, was gained by a study of people who live almost 

 entirely upon meat; e.g., certain races of hunters, fishermen, and nomads. 

 To gain this knowledge, Bunge read through a large number of articles on 

 travels, and also placed himself in correspondence with travelers. In this 

 way he established the fact that at all times and in all countries where 

 the people subsist solely upon animal nourishment, either they have no 

 knowledge of salt, or do not care for it, whereas in countries in which the 

 inhabitants subsist mainly on vegetables there is always such an unmis- 

 takable craving for salt, that it has become considered as one of the neces- 

 sities of life. This is the case in both the north and south polar regions. 

 Again, in countries in which the inhabitants live on meat and rice, there is 

 no craving for salt. Rice contains but one-sixth as much potash as 

 wheat, rye, barley, or Indian corn, one-twentieth as much as the legumes, 

 and only from one-twentieth to one-thirtieth as much as potatoes. 



Now what happens in the case of a people subsisting chiefly on vegeta- 



