56 CICATRIZATION OF WOUNDS 



wounds and that of the influence of certain retarding or 

 accelerating factors. 



He had already made some beautiful experiments on 

 cicatrization, that marvellous phenomenon which begins as 

 soon as our skin or our muscles or our tendons are wounded, 

 and stops when the lesion is repaired. In a cut, a burn, a 

 torn tissue, all the cells concerned, asleep so to speak until 

 then, wake up and multiply with feverish activity, reproduce 

 by millions, repair the damage as well as possible, and then 

 fall back into their latent life. We are no longer surprised 

 by this admirable labour because we have seen it since child- 

 hood. Familiarity kills wonder. 



'The cicatrization and regeneration of tissues are the 

 manifestations of the tendency to persist which is inherent 

 to all living organisms. We are profoundly ignorant of 

 the nature of these phenomena. They are, like the func- 

 tion of nutrition, a fundamental property of living matter. 

 It is as impossible to know their essence as it is to know the 

 essence of life. Moreover, this knowledge would be useless. 

 From a metaphysical point of view, it might be interesting 

 to know why a wound cicatrizes. But from a scientific 

 point of view, it is infinitely more important to know how 

 it cicatrizes. It would thus become possible to determine 

 the efficient causes of the complex mechanism of the 

 regeneration of tissues. That is why it is useful to study 

 the physiological phenomena of cicatrization. It is true 

 that the regenerating power escapes our methods of 

 research, but the physico-chemical processes which are 

 co-ordinated and harmonized by this directing force in view 

 of the morphological reparation can enter into our field of 

 experiment.' 



It was in 1908 that Dr. Carrel wrote these lines which he 

 later communicated to me and with which I began my Thesis 

 in 191 7. At the same time, he gave me the unpublished 

 results of his experiments. I will summarize them here so 



