It is hypothesized that the observed clumping of plasma waves in type III sources in the solar wind is due to suppression of the linear stream-plasma interaction by density inhomogeneities of scale size comparable to the characteristic amplification length. Criteria are given for when such suppression should be important. The magnitude and scaling of density inhomogeneities in the 50–200 km range near 0.5 AU is estimated from interplanetary scintillation data. This information is used to construct model sources in which plasma waves are traced and amplified with random inhomogeneities to test the hypothesis. Significant clumping occurs for inhomogeneity scales of 50 and 100 km with inhomogeneity expectation values of 4.8×10−3 and 6.0×10−4, respectively, but not for 200 km scales. Further research is suggested to determine more completely the effects of density inhomogeneities in type III sources. Further details can be found in Smith, D.F., Sime, D. 1979, Astrophys. J., in press.