306 SPECIAL HISTOLOGY. 



0-007-0-008 of a line, with fine, also dividing filaments of 0-0008-0-002 

 of a line. I have also seen in the synovial membrane itself, close to the 

 condyles of the femur, tolerably numerous nerves composed of delicate 

 fibres. 



§ 100. Development of the Bones. — In respect of their development, 

 the bones fall into two groups, viz., into those which are preformed in a 

 cartilaginous state (primary bones), and into those which from a small 

 beginning are developed in a soft blastema (secondary bones). The former, 

 while yet in the cartilaginous condition, present all their essential parts 

 (diaphyses and apophyses, body, arches, and processes, &c.), and as far 

 as their cartilaginous basis is concerned, originate like other cartilages, 

 and continue to grow more or less in the same manner. They afterwards 

 become ossified (in man, all of them) from within to without, transform- 

 ing a portion of the cartilage completely into bone, so that what was the 

 perichondrium becomes the periosteum, and afterwards attaining their 

 ultimate figure, partly by means of the remaining cartilage, which con- 

 tinuing to grow with them is successively ossified, and partly by means 

 of a soft, ossifying blastema, which is deposited layer upon layer on the 

 inner surface of the periosteum. In the second group, the bone is formed 

 from a very limited, soft, non-cartilaginous basis, and continues to grow 

 at the expense of that substance, which is continually developed anew, 

 first at the margins only, but afterwards also on the surfaces. When 

 these bones have attained a certain size, the blastema out of which they 

 have hitherto been developed may become, partially, cartilaginous, in 

 which case the cartilage stands in the same relation to the bone as it 

 does in the former instance. The greatest part of their formative sub- 

 stance, however, always remains in a soft condition, and from it, without 

 its ever becoming cartilaginous, the principal bulk of the bone is produced. 



Frequently as the development of the osseous tissue has already been 

 discussed, still, in a general point of view, the mode in which the bones, 

 as organs, originate has hitherto been little considered, and I believe 

 that I was the first, in my " Zootomical Report," Leipzig, 1849, to es- 

 tablish the principal features of the process, and in my " Microscopical 

 Anatomy," II. 1, p. 344, et seq., to trace it in its more particular details. 

 H. Meyer (1. c.) agrees with me in most of the essential points, whilst 

 Robin advances many diflerent views, with which I do not accord, and 

 has to some extent entirely misunderstood my statements. 



§ 101. The primary cartilaginous Skeleton of the human body, al- 

 though less complete than the subsequent osseous framework, is still 

 sufiiciently extensive. We find as portions of it : 1. A complete verte- 

 bral column, with as many cartilaginous, as there are afterwards osseous 



