1. Biological ageing means change of structure and function with the beginning of the autonomy of a human being up to the death of the individual. 2. Already early in the first third of life begin changes caused by ageing, which in concurrence with developmental processes increasingly predominate. 3. Thus the total biological functional capacity of an organism decreases, which we called "vitability". 4. Ageing processes do not only occur on post-mitotic cells, but also on intermitotic cells regular changes caused by ageing are to be established.