A model of polymer chains as compressible elastic spheres in flow is presented.The spherical polymer blobs are assumed to compress 711719541028 in simple Couette flow in accord with recent rheo-optic measurements on semi-dilute solutions.The experimentally determined decrease in radius with increasing shear rate is predicted by the model.Furthermore, the model predicts power law exponents usc trojans snapback hat for the viscosity-shear rate within the range of measured values for polymer chains.