Bauhaus-Universität Weimar

Titel:
The Cyclopaedia of Anatomy and Physiology, vol. 3: Ins-Pla
Person:
Todd, Robert Bentley
PURL:
https://digitalesammlungen.uni-weimar.de/viewer/image/lit29464/933/
OSSEOUS TISSUE. 
fused state of the specimen, a little dilute 
muriatic acid should be placed upon the glass 
in contact with the specimen. Solution of the 
powdered mass will instantly commence, but 
the broken granules will have disappeared be¬ 
fore the entire ones are appreciably affected. If 
at this point of the experiment the acid be re¬ 
moved and replaced by pure water, a perfect 
specimen will be gained. In examining the 
tissue under consideration it is most satisfactory 
to watch the action of the acid upon the cal¬ 
cined or steamed bone, and especially its action 
upon the small masses, for in these, when un¬ 
dergoing the action of dilute acid, the granules 
composing them become particularly distinct, 
so that their individual character may be stu¬ 
died ; and if the solvent be not removed, their 
separate disappearance may be watched as the 
superficial ones are exposed and acted upon by 
the solvent fluid. If the acid be left with the 
so treated bone for a sufficient length of time, 
all the earthy matter will be dissolved and there 
will remain a transparent indistinctly cellular 
mass, which may be supposed to be an inter¬ 
granular substance, the purpose of which was 
to unite the granules into a compact whole. 
Bone which has been treated with dilute 
acid without the previous removal of the ani¬ 
mal matter, soon loses the earthy component, 
leaving only the animal. This, however, does 
not tend to develope the granularity; indeed 
it seems, in most cases, to render it less dis¬ 
tinct than in either the unaltered or the calcined 
bone. The granules themselves are subject to 
some variety in size, commonly varying from 
the one-sixth to one-third the size of a human 
blood globule. 
Of the lamina.—The form taken by the 
bone substance is that of laminæ, and these 
laminae have a definite arrangement, so much 
so that three distinct systems may be recognised, 
namely, laminæ of the Haversian canals; 
secondly, the laminæ which connect the 
Haversian systems; and thirdly, the laminæ 
which form the surface of the bone and enclose 
the two previous orders. 
The laminæ of the Haversian canals have a 
concentric arrangement, and present, when 
divided transversely, a series of more or less 
distinct and perfect rings : see figs. 448 and 450. 
They are subject to considerable variety in 
j number, but the more common amount is ten or 
twelve. Of these, the internal lamina, that which 
forms the parietes of the Haversian canal,is most 
distinctly marked, while each succeeding one as 
you proceed outwards becomes less distinct. The 
f concentric laminæ with bone cells and central 
canal have received the name of Haversian 
system from Dr. Todd and Mr. Bowman in 
their work on Physiology. 
Connecting these Haversian systems is a 
second series of laminæ, without which the 
former would exist but as a bundle of loose 
- tubes. (Seefig. 448, c). 
In this substance we find the laminated 
arrangement less distinct, far less regular, and 
the laminæ individually subject to great 
irregularity of thickness. It is often also more 
transparent than either the Haversian or exter- 
VOL. III. 
849 
nal system. Bone cells contained in it are 
also more irregular in shape than those found 
in other situations. The last division consists 
of those laminæ which surround the exterior of 
the bone. These have greater individual 
extent, but are the least numerous. They are 
continuous with the laminæ of the Haversian 
system whenever the latter arrive at the surface 
of the bone ; the external laminæ in this case 
being continuous with the inner laminæ ot the 
Haversian system. 
Some authors have doubted the existence of 
a laminated arrangement in bone. If, however, 
young bone be examined, all doubt upon the 
subject will be dispelled, and especially if it 
be first macerated in weak muriatic acid, when 
the appearance represented in fig. 450 will be 
seen. In bone so treated the laminæ may with 
Fig. 450. 
The laminæ as they appear a fter the removal of the 
animal matter by the action of acid. 
the assistance of two needles be separated. In 
the bones of old animals the laminæ are much 
less distinct ; in these, however, they may be de¬ 
monstrated if acid be used. Though the external 
lamina is very distinct, and therefore the boun¬ 
dary of each Haversian system, yet in bone of 
advanced age the distinctness is lost in com¬ 
mon with the definite outlines of the three 
orders of laminæ. The cancelli of the can¬ 
cellous portion of bones are but enlarged 
Haversian canals, which in addition to vessels 
contain fat; the laminæ therefore which form 
the walls are those of the Haversian system. 
In connection with this division of the sub¬ 
ject, the effect of madder given to an animal 
with its food upon the osseous system may be 
noticed, since the colour is imparted to the 
laminæ. By the taking of madder into the 
stomach the effect of giving a deep red tinge is 
very soon observable. In a pigeon the bones 
were rendered brilliantly, red in twenty-four 
hours. In a young pig a similar effect was 
produced in three weeks. 
On making sections of bone so affected the 
colour is found to be present in the external 
laminæ of the bone, and in the inner laminæ of 
the Haversian system, thereby proving that the 
action of colouring takes place upon those sur¬ 
faces which lie in contact with vessels. This 
fact, with many others in this article, was men¬ 
tioned in a paper by the author read before 
the Royal Society in June of 1888. 
Of the Haversian canals.—These canals 
3 i
        

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