Flow birefringence of T2 bacteriophage DNA

The streaming birefringence and extinction angles of DNA from T2 bacteriophage in neutral aqueous buffers have been determined over a range of concentrations from 5 to 44 μg./ml. and of velocity gradients from 5 to 50 sec.^?1. Although the extinction angles are relatively small even at the lowest velocity gradients and concentrations studied, a lower limit estimate of the limiting extinction angle to shear rate ratio can be made, and this value is interpreted in terms of available dynamical theory. The statistical segment length has been estimated from the birefringence data as ～ 1100 A. This figure is in satisfactory agreement with the results of independent calculations by others.