AND HORSEHAIR AS A DRAIN FOR WOUNDS 449 



and on comparing it with the sore a week later we found that the pattern was 

 already considerably larger than the granulating surface together with the 

 cicatrizing margin already forming round it. Thus you had ocular evidence 

 of the truth that granulations have a tendency to shrink, this being one of the 

 means by which sores are diminished in extent in the healing process. 



You also observed how, when the ulcer was protected, as far as was in our 

 power, from irritation, by excluding both putrefaction and the direct action 

 of the antiseptic, the formation of the epidermic pellicle at the edge proceeded 

 with a rapidity never seen under water dressing. 



Lastly, how instructive was the result obtained by skin-grafting. You 

 saw that whereas before this operation was performed cicatrization took place 

 only at the edge of the sore, a thin superficial layer of integument, involving 

 little more than epidermis, having been removed with a sharp knife from the 

 inner side of the arm, and the shaving having been cut up on the thumb-nail 

 into small bits, which were placed in succession, with the raw surface downwards, 

 on the granulations, the grafts so planted became each one a centre of epidermic 

 growth on the sore. Thus was illustrated the general fact in pathology, that 

 new structures formed in the repair of injuries are composed only of tissues 

 similar to those in the immediate vicinity, and the equally fundamental fact 

 in physiology, that severance of a part from connexion with the body is not 

 followed by immediate loss of its vitality. 



You remember also how, having sprinkled the granulating surface with 

 a sufficient number of grafts, we placed upon the sore the remaining portion 

 of the shaving, about as large as a fourpenny-piece, and this, as you afterwards 

 saw^, took root and adhered by its entire under-surface, thus teaching us two 

 great truths. First, it showed that the surface of granulations, if thoroughly 

 healthy, may unite not merely with granulations, but with a freshly cut surface, 

 combining, so to speak, union by second intention with union b^- first intention. 

 And, in the second place, it afforded of itself conclusive evidence of a most 

 important pathological fact not yet universalty recognised, that granulations 

 have no inherent tendency to form pus ; for, before sufficient time had elapsed 

 to cause the death of the portion of integument as the result of its severance 

 from vascular connexion witli the rest of the body, all pus-formation from the 

 granulations on which it was placed must have ceased ; and not pus- format ion 

 only, but serous oozing also, which would have been equally incompatible witli 

 union of the two surfaces. No sooner did this piece of living dressing, perfectly 

 unstimulating, chemically or mechanically, protect the granulations, than pus- 

 formation and exudation of licjuor sanguinis were alike suspended. 



These, you may say, are very simple matters. Some of them, at least, 



