172 ENCHONDROMATA. 



parts must inevitably follow any farther growth. In the deve- 

 lopment of the osseous system from cartilage we accordingly 

 find a singular arrangement. When a cartilaginous epiphysis 

 has reached a certain bulk, medullary spaces containing blood- 

 vessels appear exactly in its centre ; and this gives the necessary 

 impulse for the development of true bone, which accordingly 

 begins at this very point (epiphysal nucleus). The formation of 

 vessels and of true bone has also been observed in enchondromata. 

 It is the rule nevertheless, that the individual portions of cartilage 

 should never reach a size so great as to interfere with their being 

 conveniently nourished from their circumference. 



§ 137. This implies of course that the connective tissue 

 which combines the lobules of the enchondroma into a tumour 

 (the stroma) contains an adequate number of vessels, and that 

 a sufficient quantity of blood passes through those vessels. This 

 is the case in tumours of relatively small size, and at the circum- 

 ference of the laro-er ones as well. But it is not the case in the 

 interior of the latter. On the contrar}', the vessels appear to 

 be compressed and obliterated by the pressure of the growing 

 tumour. In cxcry enchondroma of considerable size — and some 

 have been met with weighing five pounds — w^e may accordingly 

 assume that a more or less complete obliteration of the vessels in 

 its interior has taken place, giving rise to subsequent metamor- 

 phoses of its substance. 



We nearly always find calcified patches in an enchondroma. 

 The cartilao-e then exhibits the infiltration which has been 

 described at length in ^ 49. This starts now from the matrix, 

 now from the cells and capsules. The results are always the 

 same to the naked eye ; the colour of the infiltrated parts 

 becomes dark-yellow and opaque, their consistency granular and 

 friable. It has already been mentioned that this calcification 

 may occasionally be followed by a true ossification, as in the 

 normal development of bone. Reference has also been made to 

 the conversion of the cartilage into mucous tissue. This should 

 be regarded less as a degenerative process, than as a change of 

 type, as a conversion of one tissue into another tissue of equiva- 

 lent quality, which may result in the partial or complete trans- 

 formation of an enchondroma into a myxoma. It is far other- 

 wise with that softening of an enchondroma which begins with a 

 fatty metamorphosis of the cartilage-cells, their conversion into 



