THE OSSEOUS SYSTEM. 299 



many situations, appears almost homogeneous throughout, pre- 

 senting no trace of a granular structure, whilst in others a 

 structure of that kind is obscurely visible, together with minute 

 points (Deutsch), and besides these a longitudinal striatum ; 

 which last gives the whole a fibrous aspect. From this cir- 

 cumstance, many authors appear to have been led to describe 

 the bone as composed of fibres, but quite incorrectly, for 

 although the study of their development shows, that the ossify- 

 ing parts arc, to a certain extent, very distinctly fibrous, it is 

 impossible to demonstrate anything of the sort in perfect 

 bone. On the other hand, there is no doubt that a coarsely 

 fibrous appearance exists, and especially in the bone-cartilage 

 of the compact substance, as has already been remarked by 

 others, and which is probably due to the fibrous fasciculi of the 

 original blastema; care however should be taken not to look 

 upon longitudinal sections of lamellae as such fibres. 1 When 



and they rarely entirely surround the shaft of a long bone, still more rarely the flat 

 bones. In the fast-growing bones of young animals they are absent, while in adults 

 they are usually well developed in some parts; so that their presence seems to indi- 

 cate that the bone is nearly stationary in its growth. In young, rapidly growing 

 bone, the circumferential lamina; are replaced by a series which may be called the 

 undulating lamina.'. The surface of the bone sends off processes, formed of redupli- 

 cated lamina;, which eventually arch over and inclose those vessels of the periosteum 

 which lie nearest them. The spaces thus formed become the seat of Haversian 

 systems. Young growing bone, therefore, may be distinguished from that of adult 

 animals, by its being composed of Haversian systems with intervening undulating 

 lamina;. (Tomes and De Morgan, 1. c, pp. 4 — G.) — Eds.] 



1 [Messrs. Tomes and De Morgan (1. c, pp. 13, 14) adduce very good reasons for 

 believing that the fibrous appearance which may often be detected in the laminae of 

 bone arises from imperfect illumination and definition, and express their belief that 

 bone substance "is composed of granules or granular cells, imbedded in a more or 

 less clear, homogeneous or subgranular matrix." They go on to say, " Thus as 

 regards the basement, homogeneous tissue, it will be found that where lamination is 

 highly developed, the laminae have a transparent and structureless, and a more 

 opaque and granular part, to which the former appears to be the matrix. The peri- 

 pheral lamina of the Haversian systems is generally clear and free from granularity, 

 and the internal lamina sometimes presents a similar structureless appearance. The 

 matter which fills up the Haversian systems in the full-grown antlers of the Cervidas 

 affords another and a very striking example of transparent structureless osseous 

 tissue, which in this instance is the more distinct, from the absence of canaliculi in 

 its substance. Then, again, we have another instance in the clear tissue which is 

 sometimes found between the superficial Haversian systems of ordinary bone. It has 

 already been described as a non-laminated element found on the surface of certain 

 bones. In the instances already cited, and no doubt in man] others which may be 



