Influence of the antimitotic phenanthrenequinone on the cleavage of the eggs of the mollusc,Mytilus edulis L.

1. Phenanthrenequinone, in concentrations above 1∶2 M, produces cytolysis. 2. It causes blockage in the single cell stage in concentrations down to 1∶200 M. 3. The main area of antimitotic activity lies in between 1∶2 M to 1∶20 M. 4. Most of the abnormal forms are like those produced by naphthoquinone. 5. A new and so far unobserved "linear type of cleavage" is found at the three- and four-cell stages. 6. Phenanthrenequinone is relatively more toxic than naphthoquinone. 7. Phenanthrenequinone can also affect the nuclear apparatus, producing pyenosis. 8. It can also inhibit the cell cortex in the same manner as naphthoquinone: there is no evidence that in Mytilus one quinone stimulates cortical expansion and the other cortical contraction.