The century that the Medical-Surgical Friedrich-Wilhelm Institute intends to celebrate has brought about the greatest change in medicine that it has ever experienced. Tracking this change through all the various branches of knowledge that we collectively refer to as medicine would be such a vast undertaking that it would not fit into the present commemorative publication. The task that will be attempted here must naturally be more narrowly defined: it will focus on presenting the change that has occurred in the scientific foundation upon which all branches of medicine depend for their development. This work is the commemorative publication for the 100th anniversary of the founding of the Medical-Surgical Friedrich-Wilhelm Institute, written by Rudolf Virchow. The commemorative publication addresses.