A model was developed for the source of radio recombination line emission from the galactic plane. The model is based mainly on recombination line spectra observed in the direction of the supernova remnant 3C391. The H157 alpha recombination line was used with the H92 alpha spectrum to obtain a model consistent with both spectra. Other criteria were also considered. The models studied included: a cold region illuminated by 3C391; an isolated cold region; a group of hot, dense H II regions; and a low density H II nebula. The H157 alpha spectrum in the direction of the pulsar 1858+03 was also observed. It was found that one of the recombination line nebulae probably lies along the line of sight to the pulsar, which would be at a distance of 2.6 kpc. The large scale distribution of the H II nebulae was also studied. Results suggest that they exist within an annular region from 4 to about 8.7 kpc from the galactic center.