492 NUTRITION. 



Origin and Discharge of Water. It is evident that a great proportion of the water in 

 the organism is introduced from without, in the fluids and in the watery constituents of 

 all kinds of food ; hut the views of some physiologists with regard to the action of oxy- 

 gen upon the hydro-carbons in the organism have led to the supposition that water is 

 also formed in the body by a direct union of oxygen and hydrogen. The true way of 

 determining thio point is to estimate all the water introduced into the organism and to 

 compare this quantity with that which is discharged. In 1878, we instituted a series of 

 observations bearing upon this point, which will be considered again in connection with 

 animal heat. In one set of experiments, no food was taken for thirty-three and a quarter 

 hours. The observations were begun nine and a quarter hours after the last meal and 

 were continued for twenty-four hours. During the twenty-four hours, there was a loss 

 of weight of 56 ounces; the water taken was 20 ounces; the urine was collected and 

 analyzed, and the quantity of carbon eliminated in the form of carbonic acid was esti- 

 mated from standard authorities. An estimate of the heat-value of the urinary nitrogen 

 and of the carbon discharged, compared with an estimate of the total heat produced by 

 the body in the twenty-four hours, showed a deficiency in the former of more than one- 

 third. This result rendered it probable that heat had been generated in the body by a 

 direct union of oxygen and hydrogen. In another set of experiments, made some years 

 before, the water of the food and drink and the water discharged from the body were 

 carefully estimated for five days, and the subject of the experiment was weighed at the 

 beginning and at the close of the observations. The result showed a probable daily 

 excess of water discharged over the water ingested of about 12 ounces. In the discharge 

 of water by the kidneys and skin, it has long been observed that, in point of activity, 

 these two emunctories bear a certain relation to each other. When the skin is inactive, 

 as in cold weather, the kidneys discharge a large quantity of water; and when the skin 

 is active, the quantity of water discharged by the kidneys is diminished. 



Chloride of Sodium. Chloride of sodium is next in importance, as an inorganic 

 proximate principle, to water. It is found in the body at all periods of life, existing 

 even in the ovum. It exists in all the fluids and solids of the body, with the single ex- 

 ception of the enamel of the teeth. The exact quantity of chloride of sodium in the 

 entire body has never been ascertained ; nor, indeed, has any accurate estimate been 

 made of the quantity contained in the various tissues, for all the chlorides are generally 

 estimated together. It exists in greatest proportion in the fluids, giving to some of them, 

 as the tears and perspiration, a distinctly saline taste. The following table gives the 

 quantities found in some of the most important of the fluids and solids : 



Table of Quantities of Chloride of Sodium. 



Parts per 1,000. 



In Blood, human (Lehmann) 4-210 



" Chyle (Lehmann) 5-310 



" Lymph (Nasse) 4-120 



" Milk, human (Lehmann) 0'870 



" Saliva, human (Lehmann) 1 '530 



" Perspiration, human (mean of three analyses, Piutti) 3'433 



" Urine (maximum) } C 7'280 



" " (mean) > Valentin. < 4-610 



" " (minimum)) ( 2'400 



" Faecal matters (Berzelius) 3-010 



Function of Chloride of Sodium. The function of this principle is undoubtedly im- 

 portant, but it is not yet fully understood. It does not seem to enter into the substance 

 of the organized solids and semisolids as an important and essential element, but apparent- 



