1. The unfertilized Arbacia egg contains an average of 20γ x 10–3 ribonucleic acid and 0.7 to 1γ x 10–3 desoxyribonucleic acid.
2. During the first 24 hours of development, the amount of ribonucleic acid per embryo remains practically unchanged whereas that of desoxyribonucleic acid steadily increases. At the end of this period, the amount of desoxyribonucleic acid per embryo is 10 to 15 times larger than that of the unfertilized egg.