I9I4] P. B. Hawk 425 



ucts, the amino acids. These crystalline acids .with the help of 

 water now pass through the walls of the intestina into the blood, 

 which is over 90 per cent. water. Borne along by the blood stream 

 these amino acids are quickly transported to the various tissues and 

 Organs of the body. Such of the acids as are needed for cell con- 

 struction are linked together to form the basis of new cell protein, 

 water being a by-product of the synthesis. Such of the amino acids 

 as are not needed for this purpose are shorn of their nitrogen by 

 a deamination procedure, the amino acid being thus split into two 

 portions, one nitrogenous, the other carbonaceous. The ammonia 

 formed from the nitrogenous part is passed into the blood where in 

 the presence of carbonic acid ammonium carbonate is formed. By 

 the removal of water from this carbonate we obtain the correspond- 

 ing carbamate and, by the removal of water from the carbamate, 

 Urea results. The urea is then removed from the blood by the kid- 

 neys and excreted in an aqueous Solution, the urine. In the mean- 

 time the carbonaceous portion of the amino acid has been oxidized in 

 the tissues to yield energy, water and carbon dioxid being the final 

 products of this combustion. 



The varied relationships of water that are associated with the 

 proper digestion, absorption, metabolism and excretion of protein 

 are present, although in a somewhat less accentuated degree, in the 

 cases of fats and carbohydrates. In other words, the digestive and 

 metabolic transformation of all essential food stuffs is inseparably 

 and vitally associated with water. The changes being essentially 

 chemical, they require the presence of water before they can be car- 

 ried to successful completion; and the actual processes themselves 

 are almost universally accompanied by a definite change in chemical 

 structure that is associated with the gain or loss of water to the 

 molecule. For example, when we ingest sucrose (cane sugar) we 

 are ingesting a very soluble and easily diffusible substance. In spite 

 of these physical characteristics it is not available for the uses of the 

 organism because of its chemical structure. If this cane sugar 

 molecule, C12H22O11, be introduced into the human body by any 

 means other than the gastro-intestinal tract it is excreted in the urine 

 unchanged except for a certain percentage (35 per cent.), which 

 Abderhalden would have us believe is trans formed in the body under 



