FLAVORS 133 



drawn from the body itself, the quantity in the urine is less only 0.4-0.7 g. 

 per day. If after a period of deprivation plenty of phosphorus is supplied, the 

 elimination in the urine is only about 0.9 g. The absolute need of the adult 

 human body, therefore, would be 0.9 g. plus the amount in the faeces. But under 

 ordinary circumstances in P-equilibrium, the quantity eliminated in the urine 

 appears to be somewhat larger, and may be estimated at 1.5 g. Adding to this 

 the average daily quantity in the fasces (0.75-1 g.), the total requirement of the 

 adult body for P-equilibrium would be something more than 2 g. 



C. CALCIUM AND MAGNESIUM 



Both these elements are absorbed from the intestine in inorganic compounds. 

 This we know from their appearance in the urine after the administration of 

 calcium and magnesium salts. 



An unlimited absorption of Ca and Mg is impossible because of the alkaline 

 reaction of the blood, although it appears to be easier for Mg than for Ca. It 

 is also very probable that Ca occurs in the blood only in the form of a proteid 

 compound which is not precipitable by an alkaline reaction merely (Kiihne). If, 

 therefore, these elements occur in the diet in large quantities, the greater part 

 is passed out unabsorbed in the faeces. Besides, Ca and Mg, like P, are excreted 

 through the intestinal mucosa, proof of which is afforded by their occurrence 

 even in starvation fasces. (In the case of Cetti 0.07 g. Ca and 0.006 g. Mg per 

 day; in the case of Breithaupt 0.03 and 0.01 g. respectively per day.) With a 

 diet extremely poor in mineral constituents generally, Renwall observed in the 

 fasces an average of 0.16 g. Ca and 0.06 g. Mg per day. 



When we compare the herbivora with the carnivorous animals we find con- 

 siderable difference in the proportion of the calcium and magnesium excreted 

 in the urine and the fasces. In the former, only about four to five per cent of 

 the Ca and twenty-four to thirty-two per cent of the Mg appear in the urine, 

 while in the latter, the urine contains as much as twenty-seven per cent of the 

 total Ca excretion and sixty-five per cent of the total Mg excretion. 



From the few observations thus far reported, we may judge that the excre- 

 tion of Ca in the human fasces would amount to thirty-six to fifty-eight per 

 cent of the total Ca excretion, and that of Mg sixty to seventy per cent of its 

 total, the exact amount in each case depending on the power of the urine to 

 dissolve the metal. 



Very few attempts have been made to place the human body in an equi- 

 librium of Ca and Mg, and for this reason it is scarcely possible to give definite 

 figures as to the actual need for them. From the few facts at hand we may 

 conjecture that an adult man would reach an equilibrium on a daily supply of 

 0.3-0.7 g. Ca, and of something more than 0.4 g. Mg. 



12. FLAVORS 



A diet consisting of pure proteid, pure fat, pure carbohydrates, ash and 

 water, each in sufficient quantity, would not be agreeable and would not be 

 eaten except in case of extreme necessity. And yet we have in such a diet 

 everything that one needs with a single exception namely, something to give 

 the food an agreeable taste and odor ; in short, a flavor to make it palatable. 

 We must not suppose that this aversion to the pure foodstuffs is due to the 

 love of pleasurable sensations which characterizes man in the civilized state, 

 for an animal will not voluntarily eat a perfectly tasteless food, even if it 

 contains everything that he needs. 



