As appropriately outlined in the first chapter in cells was pioneered in Holland by Van Loghem and part II in this book, the history of contemporary Van Rood, and it led eventually to the discovery of blood transfusion is only three-quarters of a cen- the HLA system and its subsequent explosive de- tury old. On the surface, there is not much left in velopment. In biochemistry, the work on the ABO common between an arm to arm blood transfer and MN blood group substances has provided carried out as an heroic measure in the twenties, pointers to general features of the biosynthesis and when patient or donor had to be weighed in order role of glycolipids and glycoproteins in the cell for the physician to decide when to stop, and blood membrane, and the identification of serological component therapy of today, when several patients specificities associated with specific oligo sac- can benefit from appropriately measured and stan- chari des has proven for the first time how gene dardized amounts of various purified blood frac- products that are not proteins can exhibit Men- tions. Yet, the basic principles of blood transfusion delian inheritance.