6o 



PRELIMINARY EXPERIMENTS 



rectangular aspect (Figs. 2 and 3). 'This proves that contraction 

 stopped at the level of the graft while it continued to act 

 everywhere else.' 



In another experiment, he stimulated the epithelization of 

 a large square wound which showed no trace of epithehum 

 in the lower part by grafting a small piece of epithehum. It 

 is a well-estabhshed fact that a hving graft increases the 

 production of epithelial cells. It was then observed (Figs. 4, 

 5, and 6) that the distance between the lines tattooed in India 

 Qrafty 



FIGS. 4j 5a AND 6. EFFECT OF A GRAFT ON THE GRANULAR 



CONTRACTION 



ink on the edges of the wound, decreased in the lower part 

 (presence of granulations) while it remained constant in the 

 upper part (absence of granulations). The wound became 

 trapezoidal (Fig. 5) and when totally healed resumed its 

 primitive shape. It is therefore certain that epithelization 

 inhibits the function of contraction of the granulations. 

 When epithelization is precocious, the scar is large and thin. 

 When it is slow, the contraction is stronger and the scar is 

 thick and comparatively smaller. 



The preparation of the surface of the wound for the migra- 

 tion of the epithelial cells is also a function of the granulations. 

 But it seems that their principal role is to bring the edges of 

 the wound within a certain distance of each other, about 

 10 or 15 milhmetres in a dog. This may be deduced from the 

 fact that a wound which is 10 milUmetres broad, no longer 

 contracts. The contraction becomes useless because at a 

 distance of 10 milhmetres the secondary mechanism, namely 

 epithehzation, functions easily, as we will show farther on. 



