82 Applied Biophysics 



Concliision 



To sum up the position as it appears to a physicist : in the 

 vast majority of accidents to human beings, only skull bending, 

 fracture, and rotation are of any importance ; but, with sufficient 

 experimental ingenuity, it would obviously be possible to produce 

 injuries by other mechanisms: some of the experimenters who 

 report results due to the other mechanisms may have had this 

 ingenuity ; others may be misinterpreting their experiments. 



The treatment given here needs modification in the case of 

 injury by high velocity missiles. 



Postscript. After this article had gone to press, a film showing the 

 surface of the brain as seen through a transparent window 12 was 

 exhibited in England. It shows that in the case of a nonpenetrating blow, 

 the surface of the brain slides several millimeters along the under-surface 

 of the skull, no gap appearing between the two. Hence the brain is 

 executing a swirling movement like that in figure 4. Of course, there 

 is no proof that all the damage is due to the swirling, but no reasonable 

 person who has seen the film can doubt its importance. 



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