STRUCTURE AND DEVELOPMENT OF BONE. 
133 
occurrence of lamination. The lamina which is represented at the margin is com- 
posed of still uncalcified cells. It shows the mode in which the undulating laminae 
are formed. Fig. 33 also, taken from the fibula of a calf, shows ossified lacunal 
and osteal cells without any tendency to lamination. 
The manner in which the Haversian spaces become gradually occupied by Haver- 
sian systems is peculiarly interesting. To obtain a good view of the process, it 
is necessary to make a transverse section of the developing systems. It may then be 
seen that osteal cells arrange themselves in single file within the Haversian space 
with intermediate lines of transparent tissue, and here and there a lacunal cell ; the 
process commencing at the surface of the Haversian space, and extending gradually 
inwards till the system is completed. In fact the soft tissue takes the permanent 
form previous to the addition of the salts of bone, much in the same manner and 
to the same degree as occurs in temporary cartilage before the earthy ingredients 
are deposited. Lamination is nothing more than a definite linear arrangement of the 
osteal cells with their outlines permanently retained in the perfected bone; a cha- 
racter much more strongly marked in the bones of adult than in those of young 
animals. 
In pursuing their inquiries into the growth of bone, the authors found it necessary 
to take sections of perfectly fresh bone and to examine them in albuminous fluid ; 
spirits of wine, whether diluted or not, obscures the normal appearances, and water 
is not more favourable as a medium. 
Sections permanently mounted in dilute spirit lose a good deal of their character ; 
still the appearances are preserved with more or less of their original distinctness. 
Sections mounted in Canada balsam show some of the points remarkably well. For 
instance, the partially ossified osteal and lacunal cells are tolerably well preserved, but 
unfortunately those cells which have not received any of the indurating salts are repre- 
sented only by a transparent mass, in which but little structure can be recognized ; 
thus, the part h in fig. 32 would have appeared but as a transparent line had the 
specimen been mounted in Canada balsam. In addition to the necessity foi care in 
the examination of osseous structures, under the most favourable circumstances, as 
regards the selection of specimens and the fluid used in their preparation, it is equally 
necessary to have the more recent appliances for the illumination of the objects. 
Mr. Gillett’s achromatic condenser, with what is called the white cloud illuminator, 
renders it very easy to demonstrate points which with the ordinary miscroscopic 
apparatus are shown with difficulty. It need not however be urged, that it is 
desirable in pursuing structural anatomy to avail ourselves of the most perfect instru- 
ments that can be obtained. It is proper that the authors should, before leaving 
this part of the subject, draw some comparison between the development of bone in 
cartilage and in the softer tissues. 
Temporary cartilage, previous to the development of bone, affords a mechanical 
support and protection to the surrounding or enclosed softer tissues. These offices 
T 
MDCCCLIII. 
