PREVIOUS RESEARCHES ON GASEOUS EXCHANGE. 19 



tions were made on the Semmering. Durig discusses carefully all of 

 the factors which should be taken into consideration in experiments of 

 this nature and in the interpretation of their results. Of especial inter- 

 est is his discussion of the suitable base-line to be deducted from the 

 values found in the walking experiments. It should be noted that he 

 adheres to the basal values found with the subject lying, as he considers 

 the evidence in regard to the standing position wholly inadequate. 

 His final computations for the energy required per horizontal kilo- 

 grammeter are given in table 1, page 24. 



Observations of Amar, 1910. In a research on the metabolism of 

 Arabs, 1 Amar made numerous walking experiments with 15 subjects, 

 who ranged in weight from 59 to 78 kilograms. The experiments were 

 not made with the subject in the post-absorptive condition and loads 

 weighing from 45 to 60 kilograms were carried. The Thiry metallic 

 valve and a dry gas-meter were used. The author gives a very inade- 

 quate description of his technique. It appears, however, that Amar 

 probably calculated the heat output of his subjects from the energy of 

 the food and obtained an approximate control of his results by com- 

 puting the heat output from the actual determinations of the oxygen 

 intake and the calorific value of oxygen. Averages computed from the 

 individual figures given by the author are included in table 1, page 24. 



Observations of Amar, 1911. In a series of walking experiments 

 reported in 1911, Amar 2 used Thiry respiration valves which were con- 

 nected with a dry gas-meter. The apparatus was placed upon a table, 

 which was pushed behind the subject as he walked, and samples were 

 withdrawn and analyzed, apparently for oxygen alone. The experi- 

 ments were made in the morning, 10 or 12 hours after the taking of 

 food. Control experiments were made with the subject standing and 

 also with the subject sitting, Amar noting an increase in the metabo- 

 lism during standing as compared with sitting. His computations are 

 based upon the increase in energy expenditure while walking above 

 that in a state of repose. Especial attention is given in his discussion 

 to the variations in the load and the economic value of the rate of 

 walking. The experiments have been criticized by Brezina and Kol- 

 mer, 3 who protest against the lack of information as to the details of the 

 experiments and the technique and state that the barometric pressure, 

 temperature, and carbon-dioxide output were apparently not taken into 

 consideration. An abstract of Amar's results is given in table 1 , page 24. 



Observations of Brezina and Kolmer, 1912. -A series of walking exper- 

 iments was made by Brezina and Kolmer in Durig' s laboratory in 

 Vienna. 4 In one set of experiments the subject carried on his back a 



1 Amar, Le rendement de la machine humaine, Paris, 1910; also, Le moteur humain, Paris, 

 1914, pp. 493 and 494. 



2 Amar, Journ. de Physiol. et de Pathol. gen., 1911, 13, p. 212. 

 3 Brezina and Kolmer, Biochem. Zeitachr., 1912, 38, p. 132. 

 *Ibid, p. 129. 



