62 



PRELIMINARY EXPERIMENTS 



irregular shape, epithelization always begins at the sharp 

 angles where the distance between the edges of the wound 

 is smaller (Figs. 7 and 8). The new cells seem to attract one 

 another. Though the intimate mechanism of this phenomenon 

 escapes us, it explains the acceleration of cicatrization by 

 grafts. Carrel made the following experiment in order to 

 demonstrate this particular point. Fig. 9 shows a rectangular 



FIG. 9. EFFECT OF A GRAFT ON EPITHELIZATION 



wound in which epidermization has begun (A). A tiny 

 epithelial graft, less than i millimetre square, and taken from 

 the new epithelium just being formed, is disposed at point a. 

 A few days later the wound appears as in Fig. B. The small 

 graft has been rejoined and absorbed by the neighbouring 

 epithelium. A new graft was placed in the same manner in 

 front of the peninsula formed at (3 (C). Fig. D shows that 

 not only has the epithelial peninsula surrounded the new 

 graft but that the attraction due to the coming together of 

 the two edges can be observed on the opposite border of 

 the wound. ^ 



The cellular reparation activity, the epidermization, is 

 therefore all the greater, the nearer the edges of the wound 

 are to each other. Whereas the granular contraction acts 

 when they are farther apart. When examined through the 

 microscope, the granulations assume the aspect of a relief 

 map, showing ranges of rounded hills separated by valleys 

 at the bottom of which a certain serosity can be detected. 

 The epithelial cells, either isolated or in groups, travel on the 

 surface of this liquid. Their reunion at the point where several 



^ Reverdin had already signalled a similar phenomenon. 



