VI 



THE GROWTH OF BONE 



THE work of du Hamel proved that the perios- 

 teum is one chief agent in the growth of bone. 

 Before him, this great fact of physiology was un- 

 known ; for the experiments made by Anthony de 

 Heide (1684), who studied the production of callus 

 in the bones of frogs, were wholly useless, and 

 serve only to show that men in his time had no 

 clear understanding of the natural growth of bone. 

 De Heide says of his experiments : — 



" From these experiments it appears — -forsan 

 probatur — that callus is generated by extravasated 

 blood, whose fluid particles being slowly exhaled, 

 the residue takes the form of the bone : which 

 process may be further advanced by deciduous 

 halitus from the ends of the broken bone." 



And Clopton Havers, in his Osteologia Nova 

 (London, 1691), goes so far the wrong way that he 

 attributes to the periosteum not the production of 

 bone, but the prevention of over-production ; the 

 periosteum is put round the shaft of a bone to 



compress it, lest it grow too large. 



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