THE OSSEOUS SYSTEM. 329 



et in variis aniraalibus," Edinb. 1780), Gibson ("Memoirs of the Lite- 

 rary and Philosophical Society of Manchester," 2d series, vol. I. p. 146), 

 Bibra (1. c.), Brulle' and Hugueny (1. c.), that when animals were fed 

 upon madder, the whole of the growing bones, as well as the bones of 

 adult animals, become colored, and especially so wherever they are in 

 more immediate connection with the bloodvessels; for even the medulla 

 is colored (Bibra). For which reason also, the innermost layers of the 

 Haversian canals, the periosteal surfaces, and the vascular, young bone- 

 substance, acquire a deeper color. There are, however, still some 

 points worth investigating in this way, particularly with relation to the 

 more recent statements of Brulle' and HugueVy, who, relying upon the 

 circumstance, that, as they assert, the decoloration of growing, colored 

 bones, is eifected merely by the absorption of the colored portions, 

 believe they have found that the cylindrical bones also deposit osseous 

 substance from within, particularly in the apophyses; whilst on the outer 

 surface, absorption to the same extent takes place ; statements upon 

 which I will not, at present, give any decided opinion, although at the 

 same time I hold it as quite certain, that in many places an absorption 

 does take place, on the exterior of the bone to a greater or less extent. It 

 is only by such an absorption that the enlargement of the foramen mag- 

 num from the sixth year upwards, at which time the portions of bone 

 surrounding it are united, can be explained. And the same may be said 

 with respect to the arches of the vertebrce, and numerous vascular and 

 nerve-openings (foramen ovale and rotundum of the sphenoid bone, fora- 

 mina inter transversaria, canalis caroticus, c. $c.\ Consequently, the 

 law propounded by Serres (Meek. " Archiv," 1822, p. 455), that the 

 openings in bone enlarge by the growth of the individual pieces by which 

 they are bounded, is wholly incorrect, as applied to the openings and 

 canals in the middle of bones ; as had been already, to some extent, de- 

 clared by E. H. Weber and Henle; and even in other cases it holds 

 good only for the earliest periods. 



The periosteal layers present a certain contrast to the osseous tissue 

 developed from cartilage. The former constitute principally the firm 

 cortex of the primarily cartilaginous bone, and are characterized by th'e 

 occurrence of Haversian canals and their lamellar systems, whilst the 

 latter produces the spongy substance, and contains no vascular canals. 

 It must not, however, be forgotten that even the periosteal layers all 

 have, at first, in a certain degree, a spongy structure, and in all these 

 bones, without exception, contribute, and frequently very essentially, to 

 the formation of the spongy substance; moreover, that in the cellular 

 substance, which originates from the cartilage,. in the apophyscs for in- 

 stance, secondary layers, similar to those of the Haversian canals, and 

 of the spongy substance which is formed out of the periosteal layers, 

 only not so much developed, appear to be formed. The morphological 



