Contents

28 December 1973
Vol 182, Issue 4119

About The Cover

Embryos of the salamander Ambystoma maculatum in their gelatinous envelopes. Embryos are about 9 millimeters in length. The grey cast of the matrix is due to a mutualistic alga Oophilia amblystomatis (Chlorophyceae), which increases the survivorship and rate of development of the embryos. See page 1305. [Henry M. Wilbur, Duke University, Durham, North Carolina]