248 THE NEW ZEALAND FAMILY HERB DOCTOR. 
The blood-vessels are divided into two—the arteries and 
the veins. The first carry the blood from the heart to the 
lungs, muscles, and bones, and other tissues of the body, 
leaving, if in a heaithy condition, the material to renew the 
waste and add to the growth of the body in youth, and some- 
times adult age. Having done this, it is then partly by the 
propelling force of the heart’s action, and partly by capillary 
attraction, drawn into the veins, and conveyed to the heart, 
thence to the lungs, changed by giving off its poisonous 
earbonic acid gas, and taking in health-giving oxygen. The 
walls of the arteries are formed by three coats ; the outer, 
strong and elastic; the middle, muscular ; the fibres running 
round the tube give it a contracting power. The inner coat 
is a delicate serous membrane, smooth, to allow of a free flow 
ofthe blood. The veins, which have not the same pressure upon 
them, have also three coats, but are thinner, with little or no 
muscular action. Venous blood, with the exception of that 
returned from the lungs by the pulmonary veins to the left 
auricle, is unfit for the nourishment of the body until it is 
releived of its carbonic acid, and replenished with oxygen. 
The lymph vessels are connected with a system of glands 
which secrete lymph from the tissues. It is a clear, colourless 
fluid, which plays an important part in the healing of wounds. 
Included with these are the iacteals, which secrete the milk-like. 
fiuidirom the intestines; that, with the lymph finds its way into 
the blood through the thoraci duct, the opening of which is at 
the root of the neck, where it terminates in a large vein called the 
subclavian. 
NERVES. 
Some suppose these to be hollow vessels, conveying a fluid 
from the brain and spinal cord to the muscles and tissues, but 
& microscopic examination does not justify this conclusion. 
Perhaps the best similitude of their important function is that 
of telegraph wires conveying the stimulus or vital force to 
every part of the system. The nervous system is composed of 
three parts—the cerebro-spinal, the ganglia, and the nerves. 
The brain and spinal cord are the first. The brain is con- 
