ON MUTUAL POLARIZATION OF NEARBY PAIRS OF FUCACEOUS EGGS

We have measured the mutual polarization of populations of pairs of fucaceous eggs as a function of their distance apart. We did this in different circumstances, of which the medium's pH and washing of the eggs proved most consequential. Under circumstances in which each egg tends to initiate its rhizoid pole (or germinate) toward the other, it also tends to initiate it toward the other's rhizoid initial; however, when it tends to germinate away from the other, its germination direction is independent of the other's. We infer that rhizin (an extracellular locally effective stimulator of rhizoid initiation) is concentrated near the developing rhizoid initial and is thus a link in a regenerative process that irreversibly polarizes the egg; however, antirhizin (an extracellular locally effective inhibitor of rhizoid initiation) is inferred to be uniformly emitted by each egg and thus only modifies this process. When eggs interact through antirhizin, their mutual polarization approximates the fractional gradients calculated to be imposed upon each other by synchronous spherical sources of a stable stuff in the steady state; so antirhizin interaction is inferred to have this simple character. However, when eggs interact through rhizin, their polarization greatly exceeds such gradients; we infer asynchrony, i.e., that the faster cell in each pair sends rhizin to the other, slower one before this latter starts to emit it. These inferences, in turn, are believed to confirm rhizin as a link in the polarization process, and antirhizin as only a modifier of it. A flow of the medium through the substratum and thus between pairs interacting via rhizin fails to modify their interaction at speeds of up to 2 μ/sec; it is inferred that rhizin has a diffusion constant of the order of 10-5 cm2/sec and thus is a relatively small molecule. © 1969.