CELL-DEATH INDUCES CELL-BIRTH 



337 



from destruction of red cells which have been shed 

 into the injured tissues is decomposed, and globin is 

 thus locally produced. The cell-proliferation of healing 

 must then occur in response to it, and the remains of 

 other tissues which have been killed in the injury. 



The proliferation of cells, however, is not confined 

 to the cell-proliferation of healing. It will be shown 

 that epithelial cells will also respond to auxetics, and 

 probably some if not all other cells also respond to 

 the soluble remains of their neighbours by reproducing 

 themselves. It is true that globin does not exist in 

 the cornea, for here there is no blood supply, and con- 

 sequently no haemoglobin until some time after the 

 injury. Still, if the cornea is injured the corneal cells 

 must be injured, and the cell-proliferation of healing 

 occurs in response to the remains of the injured cells. 



Irritation is always followed by cell-proliferation. 

 Irritation means damage, and damage means cell-death. 

 Cell-death sets free kreatin, xanthin, and other auxetics, 

 and the cell-proliferation is caused by their absorption 

 by the neighbouring living cells. The greater the 

 damage, the greater will the cell-proliferation be. 



Cell-division is apparently an automatic phenom- 

 enon not in the sense that it is due to some in- 

 trinsic function or duty of a cell's protoplasm, but 

 automatic in that the death of one cell will cause the 

 reproduction of its living neighbours. If we may 

 speak of the act of cell-division by mitosis as the 

 "birth" of cells, then we may say that the number 

 of births of cells in the body depends on the number of 

 deaths. The greater the number of deaths, the greater 



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