A BIOLOGICAL PHENOMENON 



59 



represented on Fig. i. The different processes of cicatriza- 

 tion had not escaped him^ but he thought it impossible to 

 succeed in formulating a law sufficiently general to cover them 

 all. He therefore abandoned the problem to devote himself 

 exclusively to the histological side of the question, which also 

 attracted a certain number of other workers. 



This period of contraction during which the surface of the 

 wound decreases solely by means of a movement of the under- 

 lying tissue, plays an important part in the cicatrization of 

 large and medium-sized wounds and especially of the latter, 

 at any rate on dogs. When studying the rate of reparation of 

 different-sized wounds on these animals, it becomes apparent 

 that wounds which are too large do not cicatrize as quickly as 

 the others. It might almost be said that everything takes place 

 as though the activity of reparation was maximum for wounds 

 that dogs are likely to inftict on each other. 



Strange to say, it seems that the phenomenon of contraction 

 is closely dependent on the presence of the granulations. It 

 does not exist before their apparition (latent period) and it 

 stops when the epidermization is complete, that is when the 

 granulations have been covered by a thin layer of epithelial 

 cells, foundation of the new skin, which slowly invades the 

 wound from the edges. In order to ascertain whether these 

 phenomena were bound together by a relation of causality. 

 Carrel made the following experiment. 



FIGS. 2 AND 3. 



EFFECT OF A GR.'IFT ON THE GRANULAR 

 CONTRACTION 



He grafted a small piece of skin in the corner of a rectangular 

 wound covered with granulations. A deformation took place, 

 but at the end of a few days, the wound had reassumed its 



