STRUCTURE AND DEVELOPMENT OF BONE. 
135 
formative cells is almost entirely lost in the general blending of the whole into a 
subgranular mass subject to lamination, in the manner already described. 
It will therefore be in accordance with the preceding views, to regard the inter- 
columnar tissue present in primary bone, rather as an accessory element calculated 
to give support during the ossification of the lacunal cells, than as an integral and 
necessary element of osseous tissue ; for it has been shown that it offers an obstruc- 
tion to the anastomosis of the canaliculi, and that the lacunal cells preserve their 
outline so long as they are enclosed within it, instead of becoming lost in the sur- 
rounding tissue, as occurs in secondary bone. It must not, however, be forgotten 
that small patches of ossified intercoluiimar tissue may here and there be found 
between the Haversian systems, even in the bone of old subjects (Plate VIL fig. 16) ; 
so that its presence in a small amount, (as accidentally left when the Haversian spaces 
are forming), is not incompatible with the normal condition of perfect bone. 
It may also be stated in this place, that the undulating laminae formed on the sur- 
face of growing bone, although for the most part removed to make way for Haversian 
systems, are also found here and there in small patches in the bones of adults. 
The subject of absorption, as it relates to the removal of bone, has already been 
partly discussed, but something more remains to be said. Although the process of 
absorption has not, and probably cannot be seen in actual operation, yet a con- 
sideration of the relative position of the increasing and wasting parts, and of their 
conditions, will, in the authors’ opinion, justify the conclusion that the bone is re- 
moved through the agency of cells. 
In seeking to find the circumstances under which the absorption of bone takes 
place most rapidly, and to the greatest extent, the authors have been led to examine 
bones which had been placed in various conditions, both of health and disease. It 
has been already stated that bone developed in cartilage is speedily removed ; but it 
does not seem that bone formed by osteal and lacunal cells is absorbed with equal 
rapidity, although in the course of a short time it not less surely disappears. This 
difference in the rate of absorption is probably the result of the vascularity and higher 
state of development of the latter tissue. In bone developed in cartilage Haversian 
spaces have to be formed before it can be permeated by vessels ; hence in this tissue 
absorption proceeds rapidly, the process being established as soon as the bone is 
formed. In adult bone, when in a normal condition, we find here and there an 
Haversian space ; but if a bone around which the soft parts are in a state of inflam- 
mation be examined, numerous Haversian spaces will be seen. If we examine the 
same bone in the neighbourhood of that part where the inflamed is merging into the 
healthy investing texture, we shall find new osseous matter in the process of depo- 
sition on the surface of the pre-existing bone. Examples of this may frequently be 
found in the vicinity of diseased joints. 
We have here an instance of the development of new tissue, and the removal of a 
pre-existing one being set in operation, by what would appear to be a different degree 
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