CURVES 75 



S"=S'[i-k (t-tVr)] (4) 



This would enable me to calculate the curve from point to 

 point with only two values of the surface of the wound at 

 t days' interval to start from. Practically, t is always chosen 

 equal to 4. I immediately verified this formula on a certain 

 number of experimental curves. The accord from one end 

 to the other was good, much better than I had hoped. I could 

 thus, by means of a simple formula, containing only one 

 coefficient, k (which, we will soon see, possessed the advantage 

 of not being arbitrary), express, as a function of time, the 

 evolution of a very complex phenomenon. This was un- 

 foreseen. At the beginning of my studies I thought it would 

 be necessary to resort to many more arbitrary coefficients. 

 Here is a convincing example of the fact that a definite pheno- 

 menon taken as a whole, can often obey a simple law, even 

 though it is the result of an important number of factors, each 

 of which obeys laws which can individually be more compli- 

 cated. We are almost on the verge of touching that amazing 

 and disturbing co-ordination which characterizes living beings. 



The first practical application of the formula was the study 

 of antiseptics. It enabled us to establish rapidly the real 

 qualities of preconized antiseptics and to prick a number of 

 soap bubbles such as the 'cicatrizing agents' reputed for 

 accelerating the healing of wounds. 



We soon became convinced at Hospital 21 that, out of 

 approximately two hundred substances tried, only two 

 possessed an exceptional number of qualities: the nos. 30 and 

 142, as stated before. The formula only confirmed the choice 

 already made empirically. The method employed for these 

 experiments was the following one.^ A wound was sterilized 

 with Dakin's solution, prepared according to Daufresne's 

 method, or with 'Chloramine T'. The curve was calculated 



^ All technical details have been given in A. Carrel and Dehelly's 

 book, Le traitement des plaies mfectees (Masson, 1917. Collection 

 Horizon). We also experimented on the action of sunlight, of 

 artificial light, of ultra-violet rays and of oxygen. In no case could 

 we detect any acceleration whatsoever. 



