34 



August Krogh and Marie Krogh. 



trogen concentration of the urine will for some reason or other very 

 seldom rise more than a little above 2 gr. per cent. The highest con- 

 centration observed by us is 2.4 gr. in 100 cc. (curve II A. S. ^/^ 4 

 a. m.) and the largest excretion of Л^ is 4.55 gr. per hour maintained 

 for very nearly two hours (IV TV, D. ^^/g 8 — 10 p. m.) with a corre- 

 sponding elimination of very nearly 300 cc. water per hour. 



4. The most conspicuous feature of the curves is the fall in ex- 

 cretion taking place during the first 5 — 6 hours of the nights after 



Fig. 13. Exp. IV. Curves for urine and respiratory exchange. 



meat days generally between 10 p. m. and 4 a. m. and the often enor- 

 mous increase found during the last 2 hours of sleep. After carbo- 

 hydrates we find nothing of this, the excretion both of water and 

 N being fairly uniform night and day (see exp. II ^i^/ — 22^^) 



It is a constant feature that after much meat the subjects woke 

 up at about 4 and urinated, and they then slept on again for about 

 two hours. They did not drink anything during the night, and it can 

 easily be demonstrated from the respiration curves that they really 

 slept again from about 4 to about 6. 



During the first 6 hours of sleep the excretion both of N and of 

 water is diminished, and then the whole quantity retained is disposed 



