MATING REACTIONS OF ENUCLEATE FRAGMENTS IN PARAMECIUM BURSARIA

¹ From the Department of Zoölogy, University of California at Los Angeles and the Department of Zoölogy, University of Vermont

1. Comparative studies were made on the following phenomena in two races of Paramecium bursaria belonging to two different mating types: (a) the mating reaction between whole animals, (b) the mating reaction between nucleate fragments and whole animals, (c) the mating reaction between enucleate fragments and whole animals, and (d) the mating reaction between enucleate fragments.

2. In the mating reaction between whole animals a phenomenon hitherto unreported was observed: When two animals become attached there is a flattening or even an appreciable indentation at the point of union which is most striking when the area of contact is small.

3. Nucleate fragments of either race show mating reaction with whole animals belonging to the other race. The mating reaction may be followed by an intimate fusion, as in conjugation between whole animals, between the nucleate fragment and whole animal.

4. Enucleate fragments of either race give the mating reaction with whole animals of the other race. Mating reactions never occur between enucleate fragments and whole animals of the same race. Mating reaction between enucleate fragments and whole animals appears to be identical with that between whole animals, but it was never followed by intimate fusion as in conjugation between whole animals.

5. The mating reaction also occurs between enucleate fragments belonging to two different races. Controls showed that mating reactions never occur between enucleate fragments of the same race.