Fig. 2. Mass spectra of 1,8-heptadecadiene (1), 6,9-heptadecadiene (2), 8-heptadecene (3), 7-heptadecene (4), 1-heptadecene (5), 3-heptadecene (6), 1-octadecene (7), 4-octadecene (8), 5-nonadecene (9), and 6-eicosene (10) from lichens and mass spectra of their DMDS adducts.