ORIGIN OF BENIGN GROWTHS 339 



bruise. The globin so produced will assist in pro- 

 moting the cell-proliferation of healing. 



Such is the explanation of the cause of cell-division 

 in the human body as demonstrated by in-vitro experi- 

 mentation. But we think that we may go farther, 

 and suggest that the initial multiplication of the cells 

 in the human embryo may also be caused by a chemical 

 auxetic. Spermatazoa contain extractives. Possibly 

 it is these extractives, set free from this spermatozoa, 

 which, after fertilisation, give rise to the subsequent 

 cell-division in the ovum from which the embryo is built 

 up. Once the cell-division has started, it will go on in 

 response to the cell-deaths which sooner or later must 

 occur. 



As we have pointed out, kreatin is not by any 

 means the only auxetic contained in the remains of 

 dead tissues, and it is yet to be proved that there is 

 not some specificity in cell-reproduction due to some 

 at present unknown substance. We know from the 

 study of heredity that certain characteristics are car- 

 ried in the ovum and in the spermatozoon, and if they 

 are so carried, doubtless other chemical auxetics, far 

 more complex than kreatin, may be carried too. 



In the meantime we think that the knowledge that 

 dead tissues cause cell-proliferation is sufficient to give 

 an inkling as to the cause of benign growths. A 

 sudden cell-death occurring in a tissue will cause pro- 

 liferation of neighbouring cells. Of course, if the 

 initial cell-death is extensive, the cell-proliferation of 

 healing will occur which ultimately leads to the pro- 

 duction of connective tissue, which in itself may 



