﹩0\farcs 6\times 1\farcs 5﹩ aperture MMT spectra of the brightest parts of the northwest and the southeast components of I Zw 18. The spectrum of the southeast component is extracted at the angular distance of 5﹩\farcs﹩4 from the northwest component. The positions of He I lines are marked. Note that all marked He I lines in the spectrum of the southeast component are in emission while the two He I 4026 and 4921 Å lines are in absorption and the He I 4471 Å emission line is barely detected in the spectrum of the northwest component.