1. An attempt has been made to determine the viscosity of the hyaloplasmic fluid in the unfertilised eggs of Sabellaria alveolata. The extent of the Brownian movement of granules in the centrifuged eggs was determined by microcinematography. 2. The random character of the Brownian movement was masked by very pronounced streaming movements. 3. After correcting for these directed movements, an approximate value of 0.2 C.G.S. units was obtained for the absolute viscosity, which agreed with the results obtained by means of the centrifuge.