1 86 OSSEOUS SYSTEM. [sect. 99. 



With regard to their origin, they come partly from the cerebral 

 and spinal nerves, partly, also, from the sympathetic. They all 

 possess dark-bordered tubules, and, finally, run out into fine 

 branches with one to two primitive fibres, the termination of which 

 has not yet been ascertained. In man, no nerves have hitherto been 

 found in the ligaments ; but the ligamentum nuchas of the ox contains 

 some fine nerve-fibres. On the other hand, the membrana interossea 

 cruris possesses fine nerve-filaments, which come from the anterior 

 tibial nerve. Of the cartilages, I have hitherto observed only in 

 the cartilaginous septum nasi of the calf very distinct fine nervous 

 trunks of 0006'" to o - oi"' in diameter, with fibres of o'oo^'" to 

 o'ooi6"' in thickness, along with the vessels (arteries) in the carti- 

 lage-canals. In the articular capsules there exist numerous nerves, 

 yet they belong chiefly to the so-called fibrous capsules and the 

 loose areolar tissue, external to the synovial membranes ; it is only 

 in the knee-joint that I have seen nerves in the proper synovial 

 membrane. 



§ 99. Development of the Bones.— The bones, with reference to 

 their development, may be divided into two groups, viz., into those 

 preformed in a cartilaginous condition (primary bones), and into 

 those which, from a small beginning, are gradually developed in 

 a soft blastema (secondary bones). The former, even in their 

 cartilaginous condition are furnished with all their essential parts 

 (diaphyses and apophyses, bodies, arches and processes) ; and as 

 far as their cartilaginous basis is concerned, are developed like 

 other cartilages, and like these, also continue to grow more or less. 

 They then ossify ; a part of the cartilage is completely transformed 

 into bone, its perichondrium being converted into periosteum ; and 

 from this period onwards, they attain their ultimate form, partly at 

 the expense of the remaining cartilage, which continues to grow 

 with them, and to ossify successively, and partly by soft ossifying 

 blastema, which is deposited la} r er after layer upon the inner surface 

 of the periosteum. The second group of bones are formed from a 

 very limited, soft, non-cartilaginous basis, and enlarge at the expense 

 of the latter, which, at first, extends itself only at its borders, 

 but soon also increases at its surfaces. When these bones have 

 attained a certain size, the blastema, by means of which they had 

 hitherto enlarged, may be partially converted into cartilage, and 

 the cartilage so produced enter into the same relation with them, 

 as in other cases. The chief part of their formative substance, 

 however, remains soft, and the main mass of the bone arises from 

 it immediately, without having ever been cartilaginous. 



