TO MESSIEURS E. DUCLAUX AND E. ROUX.
Permit me to dedicate to you this work, which sums up the labours of twenty-five years; a very great part of it has been carried out by your side, you who have done so much to lighten my task.
When, nearly fourteen years ago, you allowed me to share your work alongside the venerated Master who founded the House where we have laboured together, you were anything but partisans of my theories; they seemed to you too vitalistic, and not sufficiently physico-chemical. In course of time you became convinced that my ideas were not without foundation, and since then you have given me warm encouragement to pursue my researches in the field that I had marked out for myself.
Working by your side and drawing largely from your vast and varied stores of knowledge, I felt myself safe from those divagations into which a zoologist, who had wandered into the domain of biological chemistry and of medical science, is likely to stray. I thank you with all my heart, and I beg you to accept the homage of this work as a testimony of my deepest gratitude and of my warmest friendship.