Initiation of Cell Division in the Arbacia Egg by Injury Substances

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Abstract
Extracts of injured tissues from the frog and clam were tested for their effectiveness in causing artificial parthenogenesis in the Arbacia egg. Injury substances were prepared according to the method descr. by Heilbrunn et al. in their studies of heat death (Physiol. Zool., 19 404, 1946). The freezing point lowering of the soln. was adjusted to slightly less than that of sea water to prevent activation by hypertonicity. The pH of the soln. was between 4 and 5. In every case, the extracts caused parthenogenesis. Neutralization of the extracts, however, caused loss of parthenogenetic activity. The effectiveness of these injury substances was compared with the effectiveness of various acids at the same pH, and the following results obtained. The avgs. of the highest % cleavage from each expt. were, for the extract, 27.08, for butyric acid, 21.18, for acetic acid, 22.95, for lactic acid, 3.05, and for phosphoric acid, 1.7. Detns. of protoplasmic viscosity showed that after an exposure of the eggs to the extract just long enough to produce the 1st signs of division, an increase in viscosity can be detected. It is concluded from these results that an acid substance is released as the result of injury. This acid of injury can cause an increase in viscosity and initiate cell division in the Arbacia egg.