184
E. IMRE FRIEDMANN AND MARGALITH GALUN
Fig. 12. Higher-power scanning electron micrograph of endolithic algal growth
in sandstone from the Negev Desert, near Nahal Timna. Specimen similar to
Fig. 11, showing relation of quartz crystals, plate-like matrix crystals and cells
of endolithic algae. χ3500. After Friedmann (1971).
within the nitrate zone are friable and traversed by numerous cracks harboring a small-celled blue-green alga, Gloeocapsa minor (Kiitz.) Hollerb.
This organism was shown to fix atmospheric nitrogen under laboratory
conditions. As no nitrogen-fixing bacteria of the Azotobacter type were
E. IMRE FRIEDMANN AND MARGALITH GALUN
Fig. 12. Higher-power scanning electron micrograph of endolithic algal growth
in sandstone from the Negev Desert, near Nahal Timna. Specimen similar to
Fig. 11, showing relation of quartz crystals, plate-like matrix crystals and cells
of endolithic algae. χ3500. After Friedmann (1971).
within the nitrate zone are friable and traversed by numerous cracks harboring a small-celled blue-green alga, Gloeocapsa minor (Kiitz.) Hollerb.
This organism was shown to fix atmospheric nitrogen under laboratory
conditions. As no nitrogen-fixing bacteria of the Azotobacter type were