The work of Bichat which appears to the most advantage is the one that we now reprint; his observing mind his experimental genius and his lucid manner of exhibiting facts are particularly observable in it. This work will have for a very long time a great influence on physiologists and physicians.The Physiological Researches on Life and Death have had more than one class of admirers. Exact minds friends of the progress of science have praised it for the great number of accurate observations which it contains the ingenious management of the experiments and the correctness of the deductions; but they have regretted that the author constantly placed life in opposition to physical laws as if living beings were not bodies before they were vegetables or animals. They have seen with regret that he offered illusory explanations of inexplicable phenomena.These grounds of legitimate criticism seem to have been the reason of the enthusiasm of another class of readers for whom whatever is vague appears to have a great degree of attraction. The readers of whom I have just spoken feeling but little interest in the new facts which the Physiological Researches contain have adopted without examination its fallacious hypotheses and attaching to them an importance which the author never did because they believed that they elucidated the mechanism[vi] of the most obscure vital operations and conducted to a true theory of medicine. Should we lament this errour? Certainly not as it has powerfully contributed to the brilliant success of Bichat's work and by means of some errours much truth has been promulgated.As the works of Bichat have now become classics and their reputation cannot be increased it is time to place young students on their guard against the errours into which the imagination of the author led him and which are the more to be feared as Bichat in order to convince has employed all the fascinations of his animated style.The memory of Bichat cannot but gain by it; the numerous truths which he has discovered will shine with a brighter light when freed from the light shades that envelope them.Such is the object of the notes to the present edition which we have endeavoured to bring up to the present state of knowledge.