Some hypothetical conclusions bearing on the evolution of cicatricial tissue can be suggested. The arterial circulation deposits in the wound chemical substances necessary for contraction of the wound and for epithelial proliferation. When the biologic process is not hindered by any special or severe bacterial infection this deposit is as regular as the circulation itself, and enables us to determine in advance the date of cicatrization. It even seems as though when the epidermization process is retarded by a slight infection the substances necessary for epidermization are stored up in the wound, and when the delay due to infection is removed the epithelium finds an accumulation of nutritive substances, and, so to speak, makes up the lost time.
Moreover, when an infection entirely or partially stops epidermization, we have observed (Experiments 3, 4, and 5) that after the infection has disappeared the progress of new epidermization is much more rapid than normally; it even passes the calculated curve. The infection apparently destroyed only the epithelium and left in the wound the chemical substances which activate epidermization.
The existence of these physical or chemical activating agents has been indicated again by two anatomical clinical facts. In treating a scalp wound in which there had been practically no epidermization for many months, we applied over the entire surface of the sterile wound dermo-epidermic grafts of fetal skin. After apparently taking, the grafts were absorbed and disappeared, but epidermization of the periphery of the wound, which hitherto had not progressed, took place abundantly, almost a hundred times as much as before.
We believe that by mathematical measurements we can solve the problem of the action of various organic fluids on the cicatrization of wounds.