The amino acid composition and subunit structure of locust vitellogenin have been investigated. Glycine was the predominant amino acid of the vitellogenin 2. By combining previous data on the free amino acids of the developing egg and on the degradation of the newly characterized vitellogenin, the daily metabolism of amino acids could be calculated. 3. Most amino acids were metabolized extensively at the beginning of embryogenesis. During blastokinesis metabolism slowed then speeded up with the approach of hatching. 4. Serine, glycine and tyrosine demonstrated metabolic activity at variance with this general trend. Serine was the most abundant free amino acid. Presumably much of the glycine released from the vitellogenin contributed to the serine pool. Tyrosine metabolism appeared to be correlated to cuticle sclerotization.
