PREVIOUS RESEARCHES ON GASEOUS EXCHANGE. 



13 



somewhat high. Katzensteiri 1 likewise considers the values too high 

 and inexact and regrets that Smith did not state whether the walking 

 was done on a level or on an incline. Although Smith gives the weight 

 of the subject and the apparatus in one instance, Katzenstein criticizes 

 the absence of body-weights for each experiment. Katzenstein's 

 further criticism, that the carrying of the apparatus by the subject was 

 a fault in the technique, is of special interest in view of the subsequent 

 use of a portable gas-meter by Zuntz and his co-workers. 



Observations of Gruber, 1891. The unusual interest in mountaineer- 

 ing, which is particularly active in Switzerland, has resulted in a large 

 number of physiological observations upon the effect of high altitudes 

 on the human body. One of the earliest of the observations, which 

 included measurements of the gaseous metabolism, was that of Gruber, 2 

 who published the results of a research carried out in the Physiological 

 Institute at Berne under the direction of Professor Kronecker. Gruber 

 himself was the subject of the study. 



Instead of using a mask with two valves, Gruber employed a tube in 

 the mouth for expiration, the nose being closed by the fingers of the 

 left hand. During inspiration the rubber tube leading to the mouth 

 was tightly closed by the teeth and air was inspired through the nose. 

 The inspired air was passed into a U-tube containing soda to absorb the 

 carbon dioxide. A rubber air-cushion, which could be compressed by 

 the arm of the subject, permitted the accumulation of the excess of air 

 during the expiration, and during inspiration this air was forced out 

 through the absorbing vessels by pressure with the arm. 



Three experiments are reported in which the subject walked without 

 other load than the apparatus. The rate of walking in the first 

 experiment was 80 steps per minute. Two of the three experiments 

 consisted of 10 minutes of walking followed by 10 minutes of sitting, 

 Gruber concluding from his results that apparently as much carbon 

 dioxide is excreted in the 10-minute rest after the short walking-period 

 as during the walking. He also made three experiments while sitting 

 in a chair prior to walking and two experiments after walking. On the 

 basis of the sitting values he contends that with walking on a level 

 the carbon-dioxide production is twice as great as with sitting. Both 

 the rest and walking experiments were made 5 or 6 hours after food. 

 Comparing the results of observations made both in trained and 

 untrained condition and considering the amount of carbon dioxide 

 produced during rest as 1, he obtained the following figures: 3 



Incorrectly stated as 1.89 by Gruber and recalculated by us. 



Katzenstein, Archiv f. d. ges. Physiol., 1891, 49, p. 331. 

 "Gruber, Zeitschr. f. Biol., 1891, 28, p. 466. 3 Ibid., p. 490. 



