STRUCTURE OF BONE. 9 
bring on collapse, deprive him of breath for some time, and leave him gasping and 
speechless on the ground; while a tolerably severe blow in that region causes 
instantaneous death. 
Anxiety seems to fix its gnawing teeth chiefly in the solar plexus, causing indigestion 
and many other similar maladies, and deranging the system so thoroughly that even 
after the exciting cause is removed the effects are painfully evident for many a sad 
year. 
By means of this complicated system of nerves the entire body, with its vital 
organs, is permeated in every part by the animating power that gives vitality and 
energy to the frame so long as the spirit abides therein. 
This is the portion of the nervous system that never slumbers nor sleeps, knowing 
no rest, and never ceasing from its labours until the time comes when the spirit finally 
withdraws from the material temple in which it has been enshrined. It is the very 
citadel of the nerve forces, and is the last’ stronghold that yields to the conquering 
powers of death and decay. 
Thus it will be seen that each animal is a complex of many animals, interwoven with 
each other, and mutually aiding each other. In the human body there is, for example, 
the nerve-man, which has just been described ; there is a blood-man, which, if separated 
from the other part of the body, is found to present a human form, perfect in proportions, 
and composed of large trunk-vessels, dividing into smaller branches, until they terminate 
in their capillaries. A rough preparation of the blood-being may be made by filling 
the vessels with wax, and dissolving away the remaining substances, thus leaving a waxen 
model of the arteries and veins with their larger capillaries. 
Again, there is the fibrous and muscular man, composed of forms more massive and 
solid than those which we have already examined. 
Lastly, there is the bone-man, which is the least developed of the human images, 
and which, when stripped of the softer coverings, stands dense, dry, and lifeless ;—the grim 
scaffolding of the human edifice. Although the bones are not in themselves very pleasing 
objects, yet their mode of arrangement, their adaptation to the wants of the animal whose 
frame they support, and the beautiful mechanism 
of their construction, as revealed by the microscope, 
give a spirit and a life, even to the study of dry 
bones. 
The accompanying illustration represents the 
appearance of a transverse section of human bone, 
as seen under a tolerably powerful microscope. 
The larger hollows are caused by the minute 
blood-vessels which penetrate the bone throughout 
its substance, and serve to deposit new particles, 
and to remove those whose work is over. They are, 
in fact, a kind of lungs of the bones, through which 
the osseous system is regenerated in a manner 
analogous to the respiration which regenerates the 
blood. In order to supply a sufficient volume of blood to these various vessels, several 
trunk vessels enter the bones at different parts of their form, and ramify out into 
innumerable branchlets, which again separate into the hair-like vessels that pass through 
the above-mentioned ‘canals. These are termed, from their discoverer, C. Havers, the 
Haversian canals, and their shape and comparative size are most important in deter- 
mining the class of beings which furnished the portion of bone under examination. 
In the human bone these canals run so uniformly, that their cut diameters always 
afford a roundish outline. But in the bird-bone, the Haversian canals frequently turn 
off abruptly from their course, and running for a short distance at right angles, again 
dip and resume their former direction. 
The reptiles possess very few Haversian canals, which, when they exist, are extremely 
large, and devoid of that beautiful regularity which is so conspicuous in the mamumalia, 
and to a degree in the birds. 
SECTION OF HUMAN BONE 
