34 Nature of the Formative Stimulus 



almost without exception tangentially disposed, that is 

 perpendicularly to the radius of the wound, and the 

 protoplasmic filaments within the cells ran parallel with 

 their axes. In correspondence with this interior cellular 

 arrangement, the intercellular bridges into which the 

 protoplasmic filaments were prolonged ran for the most 

 part from tip to tip of the fusiform cells and parallel to 

 their long axes. 



Outside this annular zone, (from 2 to 2.5 mm. outside 

 the inner epithelial border,) were found large cells in 

 which the filaments and protoplasmic bridges were 

 remarkably well developed and there also were found 

 mitoses. It is therefore in this area that new cells are 

 formed. In this zone the intercellular spaces are larger 

 than elsewhere, from 3 to 6 /* wide, whereas 1.8 to 3 ^ 

 represents the mean normal figure for the epidermis. 

 This considerable enlargement of the intercellular spaces 

 makes it possible for these cells to store up the larger 

 quantity of nutritive fluid which is necessary for their 

 more intense activity. 12 



If one admits for the moment that the intercellular 

 bridges are traversed by a continuous nervous flux this 

 result will find in this hypothesis its immediate 

 explanation. 



In order to make our idea clearer let us consider the 

 concrete case of a stream of flowing water, which at a 

 certain point divides up into several branches. Sooner 

 or later a dynamic equilibrium is established and the 

 quantity of water flowing during each unit of time into 

 each of the branches respectively will be constant. If 



12 Siegfried Garten: Die Interzellularbriicken der Epithelien und 

 ihre Funktion. Archiv fur Anatomic und Physiologic. Leipzig. 

 1895- P. 407409. 



