THE UNIQUENESS OF THE INDIVIDUAL 



course, peculiar to man, but it does not derogate from our 

 argument that they should also occur in dogs, for they are 

 found principally in those breeds (bull-dogs, pekinese) which 

 have been deliberately selected for imperfect cartilaginous 

 development. Only we ourselves, therefore, not natural evolu- 

 tion, can be held to blame. 



The third of man's peculiar shortcomings on our agenda 

 is the appalling ineptitude of wound healing in the skin, and 

 here I shall follow closely the reasoning of Billingham and 

 myself. The following comparison will make the problem 

 clear. 



If the entire thickness of the integument in the chest region 

 of an adult rabbit is excised over a rectangular area of 100 cm.^; 

 something that looks superficially like an irreparable injury is 

 produced. But, so far from being irreparable, it requires for its 

 quick and successful healing nothing more than the most 

 elementary surgical care. The surface area of an adult human 

 being is about seven or eight times as great as a rabbifs, but a 

 skin defect of the same absolute size and depth, and the same 

 relative position, cannot by any means be reHed upon to heal 

 satisfactorily of its own accord. If left to itself, it will heal pain- 

 fully slowly, and will gather up and scar; a wound of similar 

 size in the leg (which is not so much thinner than a rabbit's 

 trunk) could cause a seriously disabling injury if left untreated, 

 whether by gathering up in such a way as to constrict the blood 

 supply of the Umb or by immobilizing a joint. Such an injury 

 cries aloud for skin grafting, an operation in which a thin flat 

 slice of normal skin is removed from some undamaged part 

 of the patient's body and held in place for four or five 

 days over the area of loss. (The skin graft is removed so 

 thinly as to leave behind part of the leathery layer of the 

 skin of the donor area, and the bases of the hair shafts; the 



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