136 Metabolism of Healthy Man. 



indicating in a general way the internal muscular work and muscular tonus. 1 

 As these two factors apparently in large measure determine the total metab- 

 olism during rest, the pulse-rate can under these conditions be taken as a 

 reasonably satisfactory index of the total metabolism. Experiments are much 

 needed, using the same subject under widely varying conditions of pulse-rate. 

 That the observation of the pulse-rate should also be accompanied by a measure- 

 ment of blood-pressure is obvious, and it is probably true that a simultaneous 

 study of the pulse-rate, blood-pressure, respiration, and total metabolism will 

 show some most interesting relationships which may prove of direct practical 

 value to the practising physician. 



Water Vaporized from Lungs and Skin. 

 earlier investigations. 



The determination of the water vaporized from the human body has been 

 attempted with but few forms of apparatus, and the insensible perspiration or 

 the loss in weight has of necessity been taken by many writers as the most 

 available index regarding the amount of water vaporized from the body. 



In their classical contribution to our knowledge of the metabolism of normal 

 man, Pettenkofer and Voit 2 made a number of experiments in which they 

 determined the water-vapor output of resting man. They obtained from 828 

 to 1207 grams in 24 hours, an average of 965 grams, or 40 grams per hour. 

 With fasting man they found as an average of 2 experiments, 822 grams per 

 24 hours, and they record that while there was an actual increase on the days 

 when food was taken, the increase was not as large as they would have expected. 



An early research in metabolism that includes measurements of the water 

 vaporized from the body is the little known study of Sadovyen. 3 Using the 

 Pashutin respiration apparatus, on one day he found 1700 grams of water-vapor 

 in 24 hours, from a man, with food, having a body-weight of 79 kilos. On 2 

 other days, both of which were fasting, the subject gave off 961 and 831 grams 

 of water-vapor, respectively. Another day with food showed an output of 1265 

 grams of water-vapor. In a second experiment (fasting) which continued for 

 4 days, the water-vapor output was 730, 709, 597, and 713 grams on the 4 

 consecutive days, respectively. On 1 day of food following fast the subject, 

 with a body-weight of 75 kilos, gave off 1435 grams of water-vapor. In 

 another series of experiments, when considerable quantities of starch and sugar 

 were taken, the subject, with a body-weight of 79 kilos, gave off on 1 day 

 1579 grams of water-vapor and on a second day 1137 grams. In another 

 experiment with the same subject, with a body-weight of 77.5 kilos, he gave 

 off 938 grams of water-vapor for 24 hours. The author makes the interesting 

 conclusion that 50 per cent less water is vaporized during fasting than with food. 



1 For a further discussion of this subject see p. 248. 



2 Pettenkofer and Voit, Zeitschr. f. Biol., 1866, 2; p. 459. 



3 Sadovyen, Publications of the Russian Society of General Hvgiene, St. Peters- 

 burg, 1887-88, 12; p. 13. 



