A Stud}' of the Diet and Metabolism of Eskimos. 35 



of in a very short time. The values for the 8 hours from 10 — 6 at 

 night (see table 6, p. 39) are only slightly lower than for the day 

 periods. 



Somewhat similar, though much smaller, variations in the N ex- 

 cretion have been observed before by Rosemann ^ and by Frede- 

 RiCQ ^. In their cases, how^ever, the rise took place later namely 2 to 

 3 hours after the sleep and might be due to some influence of the mor- 

 ning meal, though it appeared also when no food was taken in the 

 morning. Fredericq thinks that the rise may be produced by the 

 custom of having a morning meal at a certain hour. Rosemann 

 however gives the same explanation as we have accepted as the most 

 probable viz.: that the functional activity of the kidneys is diminished 

 during the night and that consequently there is a retention both of 

 water and of the specific urinary substances. In our experiments 

 any influence of habitual morning meals is excluded, as it is not custo- 

 mary for the Eskimos to take food in the morning, and the rise more- 

 over took place during the last hours of the sleep and at a time when 

 the subjects would usually be asleep. 



It must be noted that we have observed a slight increase in the 

 respiratory exchange and especially in the excretion of CO2 during 

 the two hours of increased renal activity (4 — 6) (see the curves II 

 -^/7, III ^/g and Vsî IV ^^/s)- When the excretion of nitrogen is not 

 increased the respiratory exchange between 4 and 6 in the morning 

 is as a rule not higher than during the rest of the night, though there 

 is one very pronounced exception to this rule (curve III ^/g). 



In table 4 are shown 24 hour values for volume of urine and N 

 excretion. For some of the individuals experimented upon we have 

 been able to add also figures showing approximately the amounts 

 of urea + ammonia nitrogen for the 24 hours. These figures have 

 been calculated from the determinations made by means of Esbachs 

 hypobromite method. One of us ^ has investigated this method closely 

 and found that when certain precautions are observed it can be made 

 fairly accurate. The quantity of gas evolved from urea or ammonia 

 by hypobromite of sodium in alkaline solution depends principally 

 upon the ratio of bromine to Na OH in the reagent ^. The reagent 



1 Pfl. Arch., Bd. 65, 1892. 



^ Biochem. Zeitschr. Festband f. H. J. Hamburger, 1908, 277. 



^ Marie Krogh: К. D. Vidensk. Selsk. Oversigter 1913. 



* The oxidizing power of the reagent is increased with increasing quantity 

 of bromine but this involves a decrease in the production of gaseous nitrogen be- 

 cause a part of the substance acted upon is oxidized to nitric compounds. By 

 employing a reagent with 1 cc. bromine to 196 cc. 30 "/0 Na OH the volume of 

 gas evolved from urea amounts to 100 "/0 of the nitrogen present but it has been 

 found that only 99.4 "/0 of the gas is Л\ while 0.6 "/0 is carbon monoxide. The 

 oxidation is so feeble that almost the whole of the nitrogen is liberated as gas while 

 a small part of the carbon is oxidized to CO instead of CO2. 



3* 



