With the aim of establishing whether a relationship existed between longevity and senescent determinants, three kinds of experiments have been carried out.
First, the study of heteroplasmons obtained by mixing together ground mycelia of different longevities, led to observe that the resulting heteroplasmons exhibited the longevity of one parent. Two interpretations were suggested: either the elimination of one sort of determinant, or the dominance, if the two remain together.
Second, the use of heteroplasmons obtained by anastomosis allowed to follow the transmission of one type of determinants into a cytoplasm containing another type of determinants. The results are in agreement with the "invasion" hypothesis.
Finally the multiplication of senescent determinants was followed during the incubation period. The number of senescent determinants increased exponentially. The experiments demonstrated that the increase rate is different for strains of different longevities. It can be established a correlation between the increasing rate and the amount of growth necessary before the senescent morphology becomes manifest.
A common particle could be responsible of the longevity and senescence characteristics of a given race. The longevity determinant can be transformed into a senescent determinant either by a structural modification of the particle, or through a functional modification
The correspondence between the longevity determinant and the senescence factor is discussed as the correspondence of the longevity determinant to a known cytoplasmic organelles.