Induction of altered patterns of cortical morphogenesis and inheritance in Paramecium aurelia

The effect of phenethyl alcohol (PEA) on cortical morphogenesis in Paramecium aurelia in relation to the fission cycle was investigated by the method of sister cell analysis. PEA interferes with cortical morphogenesis by suppressing the formation of cortical units, presumably by the inhibition of kinetosome production. The action of PEA at different timed stages during the fission cycle shows that there are series of “transition points” beyond which PEA no longer has any effect on cell division, but still blocks cortical unit formation, while at a later time, both cell division and cortical morphogenesis are unaffected. Incompletely divided cells, “chains,” lacking oral membranelles are produced after prolonged PEA treatment. The specific inhibition of oral membranelle formation is shown by the effect of PEA on oral morphogenesis during fertilization and reorganization in the absence of cell division. The gullet condition following PEA‐treatment during conjugation is restored to normal through successive cell generations, except for those cells lacking oral membranelles. The results indicate that chemical modification of the cortex can result in persistent changes in the pattern of cortical organization.