contains only three pages. May this temperance in the summary 

 bring me pardon for the eleven hundred and fifty pages which I 

 thought necessary in order to bring the reader to this point! I 

 leave to others the delicate task of deciding whether this antithesis 

 deserves criticism or praise. I shall merely remind the reader, 

 pleading at last extenuating circumstances, that since the Institute 

 did me the honor in 1875, on the recommendation of the Academy 

 of Sciences, of bestowing upon my work the grand biennial prize, 3 

 it seemed to me that it was my duty to spare myself neither time 

 nor trouble to make the publication of my work more worthy of 

 this great award. 



Before finishing this preface, I must thank M. Grehant and M. 

 Dastre, my assistants in the chair of physiology of the Faculty of 

 Sciences, Dr. Jolyet, assistant director of the laboratory, and M. 

 Paul Regnard, assistant in the course, who aided me in my research 

 with affectionate devotion. 



P:B 

 October, 1877. 



1 See my Lessons on the Comparative Physiology of Respiration; Paris, 1870, pages 121-130. 



2 Paris. C>. Masson. 1875. Second edition. 1876. 



3 This award of the first order is given every other year, according to the terms of the con- 

 stitutional decree, "to the work or discovery which has made the greatest contribution to the 

 honor or the service of the country" in the last ten years, in rotation for each of the branches 

 of human learning represented by the five classes of the Institute. 



The triennial prize, by the decree of April 14, 1855, was decreed to M. Fizeau, in 18o6; 

 it was triennial only once, and by the decree of December 22, 1860, at the request of the Institute, 

 it became biennial, and since then the awards have been as follows: 



To Thiers (Academie franQaise), 1861. 



To Jules Oppert (Academie des inscriptions et belles-lettres), 1863. 



To Wurtz (Academie des sciences) , 1865. 



To Felicien David (Academie des beaux-arts), 1867. 



To Henri Martin (Academie des sciences morales et politiques) , 1869. 



To Guizot (Academie franQaise), 1871. 



To Mariette-Bey (Academie des inscriptions et belles-lettres), 1873. 



To Paul Bert (Academie des sciences), 1875. 



To Chapu (Academie des beaux-arts), 1877.— (Editor's note.) 



XIX 



