It consists essentially of a number of minute corpuscles or plastids, the protoplasmic substance of which is impregnated with a green coloring matter.
These are peculiar bodies which are found in the prostate, in the central nervous system, in the lung, and in other localities, and which get their name from being very like starch-corpuscles, and from giving certain colour reactions closely resembling those of vegetable cellulose or even starch itself.
For example, if it should turn out that the mass of a body is to be estimated by counting the number of corpuscles (whatever they may be) which go to form it, then a body with an irrational measure of mass is intrinsically impossible.
It is largely to researches on the bone marrow that we owe our present knowledge of the origin and the classification of the different cellular elements of the blood, both erythrocytes or red corpuscles, and the series of granular leucocytes or white corpuscles.
Whatever be the ancestral cell from which these cells spring, it is in the bone marrow that we find a differentiation into the various marrow cells from which are developed the mature corpuscles that pass from the marrow into the blood circulation.