In the thesis the gelation of the system gelatin / water was investigated by use of rheological and optical methods. The rheological properties were taken to describe the gelation in terms of the percolation theory. In order to determine the gel point and the critical exponents a potential law found by Stauffer and de Gennes that describes the development of the storage and loss modulus was used to express normalized percolation approches. This normalized percolation ansatzes delivers a single very exact gelation time and the information which range should be taken for the evaluation. Combining the storage and the loss modulus symmetrically around the gel point novel so called combined percolation functions were formulated. From these combined functions the critical exponents could likewise be determined. The simultaneous measurements of the rheological and optical properties clearly show that close to the gel point the loss and the storage modulus as a function of time as well as a function of the optical rotation could be described in terms of the percolation theory. Furthermore an aggregation model was formulated that describes the development of the storage modulus close and far away from the gel point, respectively.