A BIOLOGICAL PHENOMENON 



6i 



A beautiful experiment of Carrel's proves that an external 

 excitation is necessary to set the process of reparation going. 

 A fresh and sterile wound, carefully covered by a sheet of 

 cellophane glued to the skin and therefore completely protected 

 against any external action, does not cover itself with granula- 

 tions and does not cicatrize. In other words, the skin, which 

 is a protective element, has no reason to reappear, and therefore 

 does not reconstitute itself. 



FIGS. 7 AND 8. AT A AND B THE DISTANCE BETWEEN THE EPITHELIAL 



BORDERS BEING SMALLER (LESS THAN 1 5 MILLIMETRES), EPITHELIZATION 



IS MARKEDLY FASTER, AS WELL AS IN THE ANGLES C AND D 



3. Period of Epithelization or Epidei-mization. The begin- 

 ning of the epithelization period can easily be observed on 

 a rectangular wound which has been outlined with India 

 ink. The new epithelium, which later becomes the scar, 

 progresses at first very slowly at the surface of the granulations. 

 It is extremely thin and fragile, and there are numerous 

 factors which hinder its development. (The experiments 

 subsequently realized at the Compiegne Hospital showed 

 that the most important of them was infection). The observa- 

 tion of trapezoidal wounds shows the rapidity of cellular 

 proliferation (epidermization) at the smaller base in compari- 

 son with its slowness at the longer base. In wounds of 



