A Volatile Factor in Relation to in Vitro Spermatogenesis in the Cecropia Silkworm

The in vitro development of spermatocytes of the Cecropia silkworm is inhibited when individual cultures are placed in large chambers rather than in depression slides. The inhibition is relieved by increasing the number of cultures in each sealed chamber—a finding which demonstrates that the individual cultures interact. 2. The basis of this interaction was studied in detail. Evidence was obtained that the interaction occurs via the gas phase within the chamber by virtue of the production by the cultures of a developmental factor which is volatile. 3. The role of this volatile factor was studied in relation to in vitro spermatogenesis. Its production was detected only in cultures containing spermatocytes and hormone. These components along with the volatile factor were then found necessary for the developmental response. 4. By suitable tests it was possible to show that the volatile factor was neither carbon dioxide nor any other normal constituent of air. 5. The factor is definitely soluble in insect blood, slightly soluble in mineral oil, and relatively insoluble in water. On the basis of present evidence, it appears to be a neutral, apolar molecule.