MESSRS. J. TOMES AND C. DE MORGAN ON THE 
first described them ; but latterly, with a more correct appreciation of their nature, 
the name of lacunae has been substituted at the suggestion of Dr. Todd and Mr. 
Bowman* who have also described the Haversian canals, their surrounding lamin®, 
and their lacunm, under the inclusive term of Haversian systems. The whole sub- 
stance of the bone is made up of Haversian systems, connected by 
patches of short lamime which occupy the spaces between the systems (Plate \ I fig. 1 i). 
These have received the name of interstitial lamina: from Koluker. In addition to 
the Haversian and interstitial laminte, we have in most instances others th^ surround, 
or partly surround the whole, and form the outer surface of the bone These, from 
the position they occupy, are called the circumferential laminm. A similar senes 
more or less perfect is found to form the wall of the medullary cavity 
If the section be taken from near the end instead of from the middle of the shaft 
of a long bone, the Haversian canals will appear much larger, and in the place of 
one great central opening we shall see numerous lesser ones corresponding to 
the cancellous part of the bone. From whatever bone, or part of a bone, the sect on 
be taken, the arrangement of laminae and lacunae is substantially the same; the 
differences between the compact and cancellous portions consisting m variations m 
the relative quantities of the bone tissue and the size and number of the canals, 
and not in any real difference in the structure. 
The elongated bones of some of the vertebrata, when cut transversely throug 
their centres, are seen to be composed, at that part, of a single Haversian system. The 
rib of a Boa may be cited as an example. 
Having drawn attention to the several parts which are recognised as entering 
into the composition of bone, the authors will now proceed to describe the results o 
their investigations under the subjoined heads : 
1st. The Haversian canals and other spaces. 
2nd. The laminae. 
3rd. The lacunae and canaliculi. 
4th. The Haversian systems. 
5th. Ossified cartilage of joints. 
6th. Ossified cells. 
7th. Bone tissue. 
8th. Development of bone. 
9th. Growth of bone. j -t j 
Haversian and other Canals of Bone. —ThQ Haversian canals have been described 
by all recent writers on the subject of bone ; their variable size and not iinfrequent 
aLtomoses have been pointed out; and the fact of the larger apertures in the 
spongy parts of bone being similar in the structure of their parietes to the smal ei 
ones in the denser parts of the osseous tissue has not failed to be recognized. It may 
be remarked, that whether the canals are large or small, their section presents an 
* The Physiological Anatomy and Physiology of Man, by Dr. Todd and Mr. Bowman, vol. i. p. 109. 
