I have given the greatest pains to editing the history. I have 

 tried to collect all that has been written on the subject of my study. 

 It seemed to me that it would be very interesting for the reader to 

 have thus before him all the pieces of evidence, with infinite 

 variety of narration, frequent contradiction, and often instructive 

 repetitions. I thought it best to give the actual works of the authors 

 quoted: I distrusted even the most conscientious analyses; in my 

 bibliographic research I have repeatedly seen the affirmations of 

 an author changed to negation by a series of translations and anal- 

 yses. Besides, summarizing and analytical chapters rest the mind 

 of the reader; but each of the facts given there finds its proof in 

 the preceding extracts. 



In the second part my personal experiments are recorded. The 

 titles of the chapters show the order in which I planned their 

 exposition. A glance at the table of contents indicates that after 

 studying directly the influence of changes in barometric pressure, 

 I have devoted a few chapters to new researches on the physio- 

 logical action of carbonic acid, on asphyxia, and on blood gases. 

 The reader will see in perusing these chapters that I have not 

 wandered as far from my subject as this mere statement of topics 

 might imply; the numerous references to this part of my book that 

 I make in my conclusions give evident proof of this fact. 



In reporting my experiments, which number about 670, I have 

 used the enumerative method; all those which seem to me inter- 

 esting have been reported at length. This method has two advan- 

 tages: first, it furnishes proof of all the conclusions, and second, it 

 sometimes permits the reader to find in the account of the experi- 

 ments what the author did not see there himself. Summaries added 

 to each chapter facilitate rapid perusal of the results obtained. 

 Finally I call attention to the fact that on each point the experi- 

 ments are listed according to their date of performance; one can 

 thus take account of observations which escaped attention at the 

 beginning of the research, of improvements made by the experi- 

 menter, and consequently of the constantly lessening number of 

 causes of errors. 



Finally the third part is entitled: Recent Data, Summary and 

 Conclusions. I first discuss the history which in the first part I 

 carried down only to my own work. Then I draw conclusions from 

 my whole series of researches. It will be seen that here my agree- 

 ment with M. Jourdanet could not be carried out literally, and that 

 I could not keep from trespassing somewhat on the domain 

 reserved for him. 



The third and last chapter, whose title is General Conclusions, 



XVIII 



