Plasma
Plasma is the liquid portion of whole blood and is the medium in which nutrients, clotting agents, hormones, drugs, metabolic waste products and blood cells are suspended and transported in. Plasma mainly consists of a solution of water (90%), protein and salt, and makes up 55% of blood volume.
Both the British and Americans collected large amounts of plasma from their respective citizens, and this vital substance was administered in the field by combat medics.