BONE TISSUE. 69 



ferent from the bone tissue which appears in such elegant 

 regularity at a later day.* 



Now, how does the latter arise from the former ? 



Two different opinions exist on this subject. According to 

 the first, and we adhere to this for the most part, the osteoid 

 tissue, which is formed at the expense of, and within the fcetal 

 cartilage, the so-called endochondral bone, has not a happy 

 life. It yields to an early death, a speedy process of lique- 

 faction, in order to permit the formation of the large medul- 

 lary canals. On its surface is deposited, by the periosteum, 

 into which the perichondrium has now become changed, and 

 with the aid of a deeper osteoblastic layer, new bone tissue 

 which, with a supplementary loss of its inner layers, persists 

 in the outer portions and causes the regular, beautiful struc- 

 ture of the bone. This may be denoted as the apposition 

 theory of osteogenesis. Koelliker has recently re-entered the 

 lists for this with great energy. 



Another view rejects the resorption of the endochondral 

 osteoid tissue absolutely, and explains the transformation of 

 the irregular cavernous bone of the commencement period 

 into the regular of the later period of life, by interstitial 

 growth alone. An industrious Russian investigator, Strelzoff, 

 supported by German predecessors, has recently endeavored 

 to substantiate this with greater accuracy. 



We cannot enter further into this actually burning contro- 

 versy. The truth, according to our views, lies more towards 

 the former side. Nevertheless, the young bone certainly has 

 an interstitial growth, which Koelliker also, naturally, 

 acknowledges ; but to what degree this occurs no one can, at 

 the present time, state with accuracy. A resorption is surely, 

 also, not wanting in the normal bone. This is proved by the 

 Haversian spaces of healthy bone, if we disregard the long 

 known abnormal resorption processes. Those who deny the 

 demonstrative force of such facts are, in our opinion, not 

 to be reasoned with further. 



* The central portion of the cylindrical bone has also once had the same cav- 

 ernous structure that is presented by the epiphysis. 



