i EXCHANGE OF MATERIAL 43 



whilst the leucocytes and microcytes increased. When 0'025 grm. 

 of lactate of iron are added daily to the above diet, it is retained 

 in a greater or smaller quantity according to the impoverishment 

 which has already taken place, and the haemoglobin is renewed at 

 the same time. 



These results were confirmed in the case of dogs by the 

 experiments of Lo Monaco in the Physiological Laboratory in 

 Florence, of which I was director at the time; but while they 

 show that inorganic salts of iron can be assimilated, the results 

 of other experiments tend to prove that the iron contained in 

 organic compounds can be assimilated even more readily than 

 inorganic iron. 



The facts we have enumerated afford incontestable proof that 

 salts must be contained in a perfect diet for adults ; they are, indeed, 

 present in sufficient quantities in and combined with the ordinary 

 protein foods. 



To this rule sodium chloride is an exception ; it is the only 

 salt which it is customary to add intentionally to an ordinary mixed 

 diet, although in such a diet it is already present in the organic 

 food substances of vegetable or animal origin. 



Bunge (1874) noticed that carnivorous animals dislike and, 

 indeed, are disgusted by food to which salt has been added, 

 whereas herbivorous animals, both wild and domesticated, devour 

 such food greedily and will lick salt rocks and deposits, so much 

 so that hunters employ salt in order to attract them. The 

 explanation of this is, in Bunge's opinion, to be found in the fact 

 that vegetable foods contain four or five times as much potassium 

 as animal foods and therefore make herbivorous animals crave 

 for sodium chloride. He noticed that nomad peoples who live 

 entirely on the produce of the chase and fishing do not use salt 

 in cooking, whereas races whose diet is largely vegetarian look 

 upon it as indispensable. Kice-eaters are an exception to this rule : 

 the Bedouin tribes of the Arabian peninsula do not add salt to the 

 rice which is almost their only article of diet, because rice is poor 

 both in potassium and sodium, a fact which goes to confirm the 

 rule. 



The sodium chloride contained in the blood is necessary for 

 the formation of the hydrochloric acid in the gastric juice, the 

 dissolving of globulin in order to facilitate intestinal absorption 

 and the regulation of osmotic pressure and the isotony of the 

 fluids, etc. When a salt of potassium, such as the carbonate, is 

 dissolved in water together with sodium chloride, a partial 

 exchange of the acids takes place, resulting in the formation of 

 chloride of potassium and carbonate of soda. The same twofold 

 decomposition must take place in the plasma of the blood, which 

 always contains chloride of soda, when a very large quantity of 

 carbonate of potassium is taken. The new salts which are formed, 



