Introduction. 5 



Likhatscheff, 1 but unfortunately used for but very few experiments. With the 

 Pashutin respiration calorimeter, both carbon-dioxide elimination and heat 

 production could be determined ; the oxygen was not determined directly, but 

 by difference. The perfected apparatus, formerly at Wesleyan University, 

 therefore, is the only one previously constructed that makes possible the sim- 

 ultaneous determination of the carbon-dioxide elimination, oxygen consumption, 

 and heat production. 



As the number of physiological factors measured increases, the difficulties 

 of manipulation and the cost increase enormously: consequently we find that 

 the extent to which the different forms of apparatus are distributed is inversely 

 proportional to the cost of installation, the difficulty of manipulation, and the 

 number of factors simultaneously measured. This is especially unfortunate, 

 since it is also true that the value of the results obtained increases with the 

 number of factors simultaneously determined. Thus, in experiments in which 

 carbon dioxide alone is determined, while the research is a distinct contribution 

 to physiological chemistry, it has by no means the value that it would have if 

 oxygen were simultaneously determined ; and likewise the value of experiments 

 in which carbon dioxide and oxygen are determined is enormously increased 

 by having simultaneous determinations of heat. 



The expense of the large respiration chambers, such as those of Petten- 

 kofer, 2 Sonden and Tigerstedt, 3 and the Wesleyan University chamber, 4 has 

 precluded the general use of this type of apparatus. To supplement the re- 

 searches with these large chambers and to provide an apparatus that is at once 

 semi-portable, accurate, and relatively inexpensive, Speck, 5 Chauveau and Tis- 

 sot, 6 and Zuntz 7 have made modifications of earlier types of apparatus for 

 studying the respiratory exchange by an examination of the expired air. 



Limitations in the vse of mouth or nose appliance method. These various 

 modifications, although yielding excellent results in the hands of the origina- 

 tors and associates trained in their laboratories, have not yielded as satisfactory 

 results in the hands of physiological chemists in general as were at first hoped 

 for. It is indeed fortunate that most of the published researches carried out 

 with these different forms of apparatus were those undertaken either by Speck, 

 Zuntz, and Chauveau and Tissot in person, or by their associates ; consequently, 

 the results of their experiments are, for the most part, as accurate as can be 

 expected with apparatus of this general type. 



With this method of studying the respiratory exchange, it is necessary that 

 the subject should lie quietly breathing through a mouthpiece or nosepiece, 



1 Likhatscheff, Production of heat of healthy man in the condition of comparative 

 rest (Dissertation, Russian), St. Petersburg, 1893. 



2 Pettenkofer, Ann. der Chem. und Pharm., 1862, Supp. Bd. 2, pp. 1-52. 



3 Sonden and Tigerstedt, hoc. cit. 



4 Atwater and his associates, hoc. cit. 



5 Speck, Physiologie des menschlichen Athmens, Leipsic, 1892, p. 7; Schriften der 

 Gesellsch. zur Beforderung der ges. Naturwissensch. zu Marburg, 1871, 10. 



6 Chauveau and Tissot, hoc. cit. 



7 Zuntz, hoc. cit. 



