100 CICATRIZATION OF WOUNDS 



difference of 15° C.) took only 11 days to cicatrize a wound of 

 1-2 square centimetres. Chemical phenomena are therefore at 

 the base of the phcjiomena of tissue reparatioti. This was to be 

 expected; but in biology, as in all sciences in general, facts 

 alone must be considered. Farther on, we shall see that this 

 observation, together with another one equally based on Van't 

 Hoff 's coefficient, constitutes one of the most solid lini^s in our 

 reasoning concerning the appreciation of time. 



■ • • • 



The most important facts to be remembered in the preceding 

 pages are, first, that the evolution as a function of time of a 

 physiological phenomenon as complex as cellular reparation, 

 which involves the co-ordination, for a determined end, of a 

 series of physical, chemical, and biological mechanisms, can 

 be mathematically expressed by a very simple formula con- 

 taining only one well-defined coefficient. Secondly, that this 

 coefficient is a function of the physiological age, and that there- 

 fore it becomes possible to measure the process of ageing. I 

 do not mention the relationship to the area of the wound, for 

 we shall see, in the last chapter, that it is easy to eliminate this 

 contingency and to obtain a new constant depending solely on 

 the age.^ 



^ As a result of our studies, the problem was taken up again by 

 other workers. Certain of the proposed formulae are not worthy of 

 mention. Either they did not express the facts accurately, or else 

 their coefficients are meaningless. The excellent work of Prof. 

 Gaston Backmann, however, must be mentioned. (Ergebnisse der 

 Physiologies vol. 33, pp. 915 and 939, 193 1). With the help of my 

 experiments he was able to express the curve of cicatrization by means 

 of a formula established by him to account for phenomena of growth 

 in general. This formula expresses the facts perfectly, and in certain 

 cases follows the experimental curve more accurately than mine. 

 Unfortunately, it necessitates no less than four arbitrary coefficients, 

 which have to be determined for every wound. From my point of 

 view, this suppresses all its interest, for it is less important to be able 

 to calculate the area of a wound within one-tenth of a square cen- 

 timetre than to be able to have an idea of the principal factors which 

 intervene in the phenomenon. Backmann's formula is the following: 



log d=ko-\-k, . log {k^-T) + k. . log2 {k.,{- T) 

 where J— the absolute rate of growth or cicatrization in square centi- 

 metres. It can be seen that the calculation of a wound by this formula 

 would take a certain length of time. 



