We present a comparison of space-craft and IPS measurements of the solar wind velocity for 1973-1975, when the large scale velocity structure was very stable. From this comparison we infer a prototype distribution across a high-speed stream for the electron density fluctuations Δne in the spatial frequency range 10-4-10-2 km-1. This 'microturbulence' is more closely related to the velocity structure in a stream than to the bulk density np. Enhancements of Δne occur in the stream interaction region, but they are not as large as those of np and they peak 12 hours after the np peak. The distribution of Δne is similar to that of the large scale (106 km) magnetic field fluctuations &sgr;B, but Δne also shows a broad variation not present in &sgr;B. Overall, Δne is most closely matched to the positive velocity gradient at the leading edge of a stream.