98 CICATRIZATION OF WOUNDS 



reader to go into the details of the reasoning which led me to 

 emit the hypothesis that the simple formula 



quantitatively expressed the result due to the granular con- 



traction and that the factor — in the exponent expressed the 



acceleration due to epidermization. The comparison of the 

 two curves calculated by means of the experimental curves 

 and representing, on the one hand, the diminution of area due 

 to contraction, and, on the other hand, the total phenomenon, 

 contraction + epidermization, proved that this hypothesis was 

 justified. We could thus express the two processes inde- 

 pendently,^ and the last formula was more complete and more 

 satisfactory than the first, though less easy to use. 



I have already pointed out some practical applications of 

 these calculations. A few years later they enabled my friend 

 Dr. Ebeling, of the Rockefeller Institute, to demonstrate 

 clearly that the mechanisms which are at the base of all 

 cellular reparation are of a chemical nature. This was done 

 in the following fashion.^ 



It is known that all chemical phenomena are characterized 



by a 'temperature coefficient', the value of which is about 2-5 



(Van't Hoff's coefficient). This means that for every rise in 



temperature of 10° C. the rate of the reaction is a little more 



than doubled. Conversely, for every diminution of 10° C, 



the rate of the reaction is divided by a factor approximately 



equal to 2-5. This criterium is used when one does not 



exactly know how to interpret a new phenomenon nor what 



hypotheses can be eliminated a priori. For example, in the 



early days of radio-activity, before 1900, scientists began by 



trying to measure the temperature coefficient. But no matter 



what the temperature of the reaction, one hundred degrees 



below zero or several hundred degrees above, the rate of the 



phenomenon remained the same. The production of what 



^ Lecomte du Noiiy, loc. cit., Journ. of Exp. Medicine, 19 19. 

 ^ A. H. Ebeling, Jowr«. of Exp. Medicine, vol. 35, p. 657 (1922). 



