A scientist is shown holding a test tube of blood. He places it into a centrifuge in order to separate the plasma from the blood cells. Once the plasma is separated, it is heated to solify the proteins in the blood. The heat evaporates the water from the plasma, leaving salts. The result is shown in magnification. Next, the film looks at the structure of blood cells. Blood is taken from a man's finger and looked at under a microscope. The blood cells are shown. Another blood sample is stained, in order to clearly show the structure of the blood cells. Labels point out red blood cells, white blood cells and platelets.