36 INORGANIC FOODSTUFFS 



citrate will react with sodium chloride to form potassium chloride and 

 sodium citrate, in accordance with the equation: 



CHzCOOK CH 2 COONa 



I /OH I /OH 



C + 3NaCl ' C + 3KC1 



I \COOK 



\COONa 



CHzCOOK CH 2 COONa 



and an excess of sodium citrate appears in the blood together with an 

 unusual excess of potassium chloride. Of course a similar interchange 

 would take place, with analogous results, if the salt ingested were 

 potassium tartrate, malate or any other of the organic salts of potas- 

 sium which are so frequently abundant in vegetable tissues. 



Now it is a function of the kidneys, as the reader will soon come to 

 appreciate very fully, to keep the composition of the blood very 

 nearly constant. They act, in fact, with the utmost precision, picking 

 out and rejecting abnormal or excessive constituents. The composition 

 of the blood cannot vary beyond the slightest extent without the 

 supervention of grave disturbances involving all the tissues of the body. 

 As a result of the ingestion of potassium citrate, tartrate, malate or 

 other potassium salts which are found in vegetables, we have seen that 

 a new salt of sodium is formed in the blood-plasma, to wit, sodium 

 citrate, tartrate, malate or what not. This abnormal constituent is 

 straightway picked out and eliminated by the kidneys, together with 

 as much as possible of the excess of potassium chloride, and thus as a 

 result of the ingestion of potassium salts the blood is robbed of both 

 sodium and chlorine. 



This theoretical deduction can very readily be illustrated experi- 

 mentally. Von Bunge collected his urine from day to day and 

 measured the diurnal excretion of sodium. He then simply added 

 18 grammes of K 2 O, in the form of citrate or phosphate, to his daily 

 diet. The twenty-four-hour excretion of sodium (estimated as Na 2 O) 

 immediately increased by 8 grammes. Now 18 grammes of K 2 O is 

 not at all an unusual amount to ingest along with a vegetable diet. 

 If one were to satisfy one's protein requirements with potatoes, as 

 many Irish peasants do, for example, one would obtain no less than 

 40 grammes of K 2 O per diem. 



One result of subsisting upon a vegetable diet, therefore, is a con- 

 tinual abstraction of sodium and chlorine from the blood. Now the 

 blood resists most strongly any alteration in its composition. The 

 reader will come to appreciate more and more clearly as this work 

 progresses, how intimately the most fundamental activities of the body 

 are dependent for their continuance upon the unalterable composition 

 of the blood. The slightest alteration even in the ratio of sodium to 

 potassium in the blood would work havoc with our tissue-activities. 

 Hence the blood must recoup itself, and it can only recoup itself by 



