4 RESPIRATORY EXCHANGE OF ANIMALS AND MAN 



Reiset [1849] it was found incidentally that hydrogen and methane 

 are sometimes exhaled from the animal body, and these authors 

 concluded further from their experiments that the atmospheric nitro- 

 gen was not completely inactive but did take a certain, though very 

 variable, part in the respiratory processes. A few other gases have 

 since been supposed or shown to be regularly or occasionally exhaled 

 from the body ; but while the exhalation of carbon dioxide in all 

 animals and the absorption of oxygen in almost all belong to the 

 fundamental functions of the organism the other gases are of com- 

 paratively minor importance. 



These latter are briefly dealt with in a special chapter, the third, of 

 the present monograph. 



The respiratory exchange in the strict sense of the term comprises 

 only the oxygen intake and the elimination of carbon dioxide, and 

 with the quantitative aspect of these processes it is intended to deal 

 more fully, treating first their general physiological significance (Chap- 

 ter I), then the methods of studying the respiratory exchange quanti- 

 tatively (Chapter II), and finally attempting a review of the results 

 obtained (Chapters IV to IX). 



A comprehensive treatment of almost the whole of this field (ex- 

 cluding the results obtained on invertebrate animals) has been given 

 before by Jaquet in 1903 [Ergebn.], 1 and parts of it have been treated 

 repeatedly. Reference must be made especially to Oppenheimer's 

 " Handbuch der Biochemie" [Op.] 1 in which Loewy has written an 

 account of the respiratory exchange of man and warm-blooded animals, 

 while Cronheim has treated the cold-blooded vertebrates and Weinland 

 has brought together the literature concerning the biochemistry of the 

 invertebrate animals. R. Tigerstedt has described respiration apparatus 

 and methods in his " Handbuch der physiologischen Methodik " 

 [T.M.], 1 and in Winterstein's "Handbuch der vergleichenden Physio- 

 logic" [W.] 1 he has given a very useful review of the temperature and 

 heat production of animals both warm-blooded and cold-blooded. 



The writer feels greatly indebted to these predecessors and to 

 several others. Only by constant reference to them has it been pos- 

 sible to trace out a course, more or less satisfactory, through the ocean 

 of literature. 



1 The abbreviations here given are used in the following chapters for reference to 

 "comprehensive treatises," the titles of which are given in the bibliography on p. 151. 



