Lymph can be defined as blood minus RBCs. Lymph is a clear, colourless fluid, similar to plasma but with less protein. It is a mobile connective tissue like, blood and is fomed by the filtration of blood. Microscopic examination of lymph depicts that it contains a large number of leucocytes (mostly lymphocytes), ranging from 500 to 75,000 per cubic mm. No blood platelets present.