476 LECTURE XIX. 



transformation of its tissue must take place, the chon- 

 drine-containing basis-substance must become converted 

 into a gelatine-yielding intercellular substance. 



I have, moreover, gentlemen, made a series of prepa- 

 rations from ricketty bones for you on the one hand, 

 because rickets above all offers an especially favourable 

 opportunity for obtaining an insight into several processes 

 of the normal growth of bone, which in other cases are 

 obscured by the presence of calcareous salts and on the 

 other hand, because you will thus form some idea of the 

 peculiarity of this process, as such. 



Rhachitis, has, as you are aware, bv^ more accurate 

 investigation been shown to consist not in a process of 

 softening in the old bone, as it had previously generally 

 been considered to be, but in the non-solidification of the 

 fresh layers as they form ; the old layers being consumed 

 by the normally progressive formation of medullary cavi- 

 ties, and the new ones remaining soft, the bone becomes 

 brittle. But besides this essential feature of the non- 

 occurrence of calcification in the parts, there is displayed 

 also a certain irregularity in growth, so that stages in the 

 development of bone which, when the formation is nor- 

 mal, ought to set in late, set in at a very early period. 

 In normal growth, the pointed processes, in which shape 

 the calcareous salts shoot up into the cartilage, form, along 

 the margin of calcification, such a completely straight line, 

 that it should almost be described as mathematically 

 regular. This condition ceases to obtain in rickets, and 

 the more so, the greater the severity of the case ; inter- 

 ruptions occur in such a way, that in some places the 

 cartilage still reaches a long way down, whilst in others 

 the calcification has mounted up to a considerable height. 

 These uncalcified parts sometimes become so completely 

 separated from one another, that they remain forming 

 specks of cartilage in the midst of the bone, and sur- 



