264 THE EVOLUTION OF CONTINUITY 



whole we may regard such a lipoma as representing the late 

 development of unnaturally arrested young somatic tissue 

 at a time when it is not wanted, and long after its absence 

 has been made good. It is young tissue which arrives late 

 when there is no place for it in the well-balanced cell-republic 

 of the body. 



But as regards the size the tumour may grow to, two 

 possibilities offer themselves. (1) That the tumour may 

 grow to an indefinite size, being, with respect to multiplica- 

 tion of its cells, completely independent of the balancing 

 restraint imposed on normal tissue. (2) That this complete 

 independence does not obtain, but that the product of the 

 unnaturally arrested cells is only free to multiply till it 

 fulfils its thwarted destiny, or to become the cells it would 

 have become had there been no unnatural arrest. Experience 

 does not lead us to expect that a lipoma after reaching a 

 certain size will stop growing. 



The lipoma mentioned is an example of a homologous 

 tumour. One simple and heterologous may be exemplified 

 by a myxoma arising in fat tissue, or a chondroma in bone. 



Here — and so far our theory is more or less that of 

 Conheim — we presume the same unnatural or premature 

 arrest to have occurred, but at a slightly earlier stage of 

 development, before fat or bone differentiation had taken 

 place ; the release from arrest occurring after maturity. 

 In such cases there may at times be additional evidence 

 of character-control, for sometimes the mucous cells of the 

 myxoma give rise later on to fat cells, or the chondroma 

 may begin to form bone ; mucous tissue being the normal 

 precursor of fat, as cartilage is of bone. 



In contrast with this, fat tumours have been known to 

 degenerate and produce mucous cells. If this be true 

 degeneration, it must then indicate diminishing control, 

 and conceivably if degeneration went far enough embryonic 

 cell-character would appear and malignancy be exhibited. 

 But the possibility of some mucous cells having been un- 

 naturally arrested along with fat cells must be borne in 

 mind. 



It is reasonable to suppose that no single factor is 

 constantly at work in causing the release from unnatural 



