The intrinsic viscosities of five different molecular weight polystyrenes in cyclohexane were measured at different temperatures. The temperatures cover three regions : above the theta point, at the theta point and below the theta point. The data were analysed with the theoretical framework on critical phenomena as a guide line. Although the collapsed region and the totally collapsed region vary with the range of molecular weight, the scaling law appears to be valid. There is a one-to-one correspondence of an observable in one regime to another regardless of the number of links.