CHAPTER XLIII.

892. Why do we know that the blood has become endowed with vital powers?

Because, in the course of its formation, it has not only undergone change of condition and colour; but, if examined now by the microscope, it will be found to consist of millions of minute cells, or discs, which float in a watery fluid. The paste produced by mastication consisted of a crude admixture of the atoms of food; the cream (chyme) formed from this in the stomach, presents to the microscope a heterogeneous mass of matter, exhibiting no appearance whatever of a new organic arrangement; the milk (chyle) which is formed in the intestines is found to contain a great number of very small molecules, which probably consist of some fatty matter; as the chyle progresses towards the thoracic duct ([Fig. 50]), it appears to contain more of these, and slight indications present themselves of the approach towards a new organic condition.

But wherever vitalisation begins, no human power can say with confidence. Yet there can be no doubt that the blood is both organised and vitalised, and that it consists of corpuscles, or little cells, enclosing matters essential to life.

"But they that wait upon the Lord shall renew their strength; they shall mount up with wings as eagles; they shall run and not be weary; and they shall walk and not faint."—Isaiah xl.

893. Why does the blood circulate?

Because all the bones, muscles, blood-vessels, nerves, glands, cartilages, &c., of which the body is composed, are constantly undergoing a change of substance. It is a condition of their life, health, and strength, that they shall be "renewed," and the blood is the great source of the materials by which the living temple is kept in repair.

894. How is the body renewed by the blood?