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And this, of course, is only one of a score of ways in which the leucocytes literally pro patria moriuntur. Our whole alimentary canal is continually patrolled by their squadrons, poured into it by the tonsils above and Peyer's patches below; if it were not for them we should probably be poisoned by the products of our own digestive processes.
In children under one year of age, the normal average is from 10,000 to 20,000. Absence of Leucocytosis Leucopenia. In certain infective diseases the number of leucocytes in the circulating blood is abnormally low 3000 or 4000 and this condition is known as leucopenia.
It is probable that the sensitive and travelling leucocytes of our invertebrate ancestors have powerfully co-operated for millions of years in the phylogenesis of the advancing animal organisation. The red blood-cells have a much more restricted sphere of distribution and activity.
Into the wedge-shaped, elastic clot which now fills the wound from bottom to top like jelly in a mould, the leucocytes or white blood-cells promptly migrate and convert it into a mesh of living cells.
The protective effects of the inflammatory reaction depend for the most part upon the transudation of lymph and the emigration of leucocytes. The lymph contains the opsonins which act on the bacteria and render them less able to resist the attack of the phagocytes, as well as the various protective antibodies which neutralise the toxins.
There is enough of climbing to call into exercise long unused muscles, the granite blocks are rough, angular and irregular enough to exercise eyes, hands and feet to keep one from falling, and the lungs are filled with balsam-ladened mountain-air, fresh from God's own perfect laboratories, healing, vivifying, rejuvenating, strengthening, while the heart is helped on and encouraged to pump more and more of its blood, drawn from long almost quiescent cells into the air-chambers of the lungs, there to receive the purifying and life-giving oxygen and other chemical elements that multiply the leucocytes vastly and set them at work driving out the disease germs that accumulate and linger in every city-living man's and woman's system.
To this process Metchnikoff gave the name of phagocytosis, and he recognised two forms of phagocytes: the microphages, which are the polymorpho-nuclear leucocytes of the blood; and the macrophages, which include the larger hyaline leucocytes, endothelial cells, and connective-tissue corpuscles.
By means of their amoeboid movement they are enabled to worm themselves through inconceivably minute apertures in the blood vessels, and attack and devour peccant matter wherever it may have effected a lodgment. These white corpuscles are also known as leucocytes, and their increase in number when they are called upon to resist bacterial invasion is spoken of as hyperleucocytosis.
The streptococcus has less capacity of liquefying the tissues than the staphylococcus, so that pus formation takes place more slowly. At the same time its products are very potent in destroying the tissues in their vicinity, and so interfering with the exudation of leucocytes which would otherwise exercise their protective influence.
The edema of the brain, irregular pink mottlings of white substance, and an exudative lesion of one focus in the pia mater of the right side suggested an encephalitis more marked on the right side. Microscopically a few small vessels showed plugs of polynuclear leucocytes. The nerve cells were affected by various acute changes.
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