As already stated, the blood is not really a red fluid. It is seen with the microscope to be made up of a clear fluid called plasma or liquor sanguinis, which contains an immense number of little disc-shaped bodies - red corpuscles - and a few colorless protoplasmic cells - white corpuscles - so that the living blood may be physically tabulated, giving approximately an estimation of the relative amounts, thus: -

Fig. 95. Human Blood after death of the elements. The red corpuscles are seen in different positions showing their shape, some also are seen in rolls. Only one white cell (w) is seen, misshapen and entangled in fibrin threads.