In the same way when any granule or particle comes in its way the corpuscle wraps a pseudopodium around it, and then withdraws the pseudopodium with the contained particle into its own substance. By means of these ameboid properties the cells have the power of wandering or emigrating from the bloodvessels by penetrating their walls and thus finding their way into the extravascular spaces. A chemical investigation of the protoplasm of the leucocytes shows the presence of nucleoprotein and of a globulin. The occurrence of small amounts of fat, lecithin, and glycogen may also be demonstrated. Each contains a central chromatin mass resembling a nucleus.
Blood platelets possess the power of ameboid movement.
When blood is shed they rapidly disintegrate and form granular masses, setting free prothrombin and the substance called by Howell thromboplastin. It is doubtful whether they exist normally in circulating blood.