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C. M. Child 



however, the contraction following the wound is so great that the 

 various parts of the circumference of the wound are closely approx- 

 imated. In such cases the margin of the thin new tissue, after it 

 has filled the various angles of the puckered margin, forms a 

 circle. If this circle is not too large, i.e., if its curvature is suffi- 

 ciently great, growth of the new tissue continues, the circular 

 opening becomes smaller and is finally closed (Fig. 6). If the 

 opening is above a certain size the new tissue ceases to grow and an 

 opening remains permanently, or until other conditions are estab- 



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lished. In my earlier paper I called attention to the similarity 

 between the growth of these thin membranes of new tissue and 

 the behavior of a fluid or semi-fluid film, and suggested that sur- 

 face-tension probably constituted a factor in the process of out- 

 growth (Child '04a, pp. 66-74). The fact that the rapidity of 

 growth of the new tissue increases with the concavity of the free 

 margin or the acuteness of the angle between two portions of the 

 margin (Fig. 5) and, on the other hand, ceases as the margin 



