The Langmuir waves which are resonant with typical type III solar radio burst electrons have a frequency so little above the ambient plasma frequency that they should be strongly affected by known density fluctuations. Some consequences of this observation are worked out, and the expected consequences are demonstrated in the observations of the Langmuir waves from two quite different bursts, of November 4, 1997, and January 19, 1998. ¿ 1999 American Geophysical Union