THE IMPERFECTIONS OF MAN 



perplexities of laymen might be set at rest if it could be shown 

 that evolution is very much a fallible, makeshift affair, and that 

 loss of fitness in one regard is often the charge for some more- 

 than-compensating gain. I choose the imperfections of man as 

 the subject of this essay, because man''s superlative biological 

 status is hardly to be questioned, and shall take three examples 

 of his falls from grace: his susceptibility to haemolytic disease 

 of the newborn; the mechanical shortcomings of his upright 

 carriage; and the ineptitude of wound healing in injuries of his 

 skin. Of these, the first is familiar enough, and I shall only deal 

 with its broader aspects; the second is well understood but not 

 yet widely known; and the third will be unfamiliar to all except 

 a few specialists in the theory of wound healing. 



Haemolytic disease of the newborn is the general name given 

 to a variety of affections (kernicterus, icterus gravis, hydrops 

 fetalis) marked by grave and sometimes fatal abnormalities of 

 the blood and blood-forming organs; its interpretation, which 

 we particularly associate with the names of Levine, Land- 

 steiner and Wiener, is one of the great triumphs of modern 

 clinical biology. Briefly, it is an immuriological disease; it 

 depends upon the active immunization of the mother against 

 blood group substances (chiefly those of the Rhesus and Kell 

 systems) absent from her own tissues, but present in the tissues 

 of her child. Like many forms of allergy and hypersensitivity, 

 and like the reaction that forbids the use of one person''s skin to 

 repair another''s, haemolytic disease can be described as a mis- 

 carriage of immunological justice — a harmful and apparently 

 wanton aberration of what is properly and primarily a mech- 

 anism of defence. 



Haemolytic disease of the newborn is a peculiar menace to 

 human beings for the following reasons. If it is to occur at all, 

 two qualifying conditions must be satisfied at the outset. First, 



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