
NOTICES OF MEETINGS. 43 

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support and give attatchment to the muscular portion of our economy, and to 
enclose our vital parts with a firm and protective strength to shield our lungs, 
brain, digestive, and other important organs from external violence. Fresh 
bone is white externally, and deep red within. On examination, it has two 
kinds of tissue, one the external dense and ivory like, the z¢erna/ consisting of 
slender fibres and lamella, which join to form a reticular structure. This is the 
cancellous, from its resemblance to lattice work. The relative quantities of 
these two tissues vary in different bones, and in different parts of the same 
bone, as strength or lightness is required. Minute examination of the ivory 
like external crust shows it is very porous, so that the difference in structure 
between it and the internal cancellous structure depends merely upon the 
different amount of solid matter, and the size and number of spaces in each, the 
cavities being small in the compact tissue, and the solid matter between them 
abundant, whilst in the cancellous structure the spaces are large, and the solid 
matter diminished in quantity. By steeping bone in diluted nitric acid, or 
muriatic acid, we chemically remove the earthy portion of bone, leaving a 
tough semi-transparent substance, which retains its original shape. This is 
often called cartilage, but in fact it only requires to be boiled under pressure, 
when it will be seen to be nearly all gelatine. To get rid of the organic matter 
we have only to subject the bone to good clear fire, and we obtain the earthy 
portion of the bone. Both constituents retain the. singular property of remain- 
ing unaltered in chemical composition after a lapse of centuries. Bones of the 
head contain more earthy matter than the bones of the trunk, and so also have 
the long bones of the extremities; as we grow older the earthy matter pre- 
ponderates. Hence old people’s bones are easily broken. Children’s bones 
often bend, and may be straightened without a fracture, or may be fractured 
but not separated, like a green wood,—hence, called greenwood fracture. 
In children, where the animal mattet preponderates, it is often found the long 
bones often bend, either from the action of the muscles or from violence. Some 
of the diseases to which bones are subject depend on the disproportion of the 
organic or animal matter to the earthy. Thus in rickets, the bones become 
bent and curved, either through the weight of the superincumbent body or 
action of muscles ; this is from defect of nutrition not supplying the necessary 
earthy matter. In the skeleton of a rickety subject the animal or soft tissue has 
been found to be as high as 79-75, while the earthy proportion has only been 
20-25. As to the form of bone, nature has made no mistake, but has afforded 
the architect many examples of strength and beauty, as exemplified in the arch 
of the foot and cranium. The long bones are hollow cylinders, in which is 
found medullary matter, commonly called marrow, forming a soft envelope for 
the blood vessels, and which is contained in an inner lining similar to the 
external periosteum. On examining the surface of most bones, there will be 
found little eminences or processes, tuberosities, tubercles, spines, ridges or 
lines ; there are also various depressions, such as fossa grooves, furrows, fissures 
and notches. These all give attatchments to the various muscles, or go to form 
the various articulations or joints ; if a fine section of long bone, transverse, is 
seen under a low power, a number of apertures are seen surrounded by con- 
centric rings, with small dark spots, grouped around, also in a concentric form 
the apertures, which are dark looking, are the Haversian Canals, called after 
the discoverer (Clopton Havers): the concentric rings are sections of the 
lamelle, which are developed round the Haversian Canals ; the little dark spots 
are called Jacun@. The canals afford a passage to the minute blood vessels 
which go to nourish the bone; they are lined by a delicate membrane continuous 
with the periosteum. The ferzosteum is the fine skin covering all bones, and 
supports a dense network of fine blood vessels, which give nourishment to the 
dense external tissue of bones; the cancellous internal structure is supplied by 
blood from vessels which perforate the external dense structure through foramens. 
Bones are well supplied with blood vessels, and sometimes bleed very freely 

