Total Number Of Generations Research Articles

In a former communication it has been shown that in our pedigree cultures of Spathidium spathula, exconjugant lines, in the great majority of cases, exhibit a higher rate of division during the first fifteen days than the parent lines.1 The purpose of the present paper is to summarize briefly the results to date with respect to the effects of conjugation as exhibited later in the life history of the pedigree lines. 1. Conjugation in the majority of cases increases the length of life of the exconjugant line, so that it lives after the death of the parent so-called “non-conjugant” line. This is shown by the fact that of forty-seven exconjugant lines, thirty lines lived longer; four lines lived to essentially the same date; and thirteen lines died before their respective parent lines. 2. The total number of generations attained by the exconjugant exceeds those attained by the parent from the date when the exconjugant arose to the death of the parent in about eighty per cent. of the lines. Of fifty-two comparable lines, forty-one lines exceeded their respective parent lines in number of fissions; two practically equalled; and nine lines did not attain so many generations. The fact is evident that conjugation increases the number of fissions to a total which could not otherwise have been reached. 3. If the period be considered during which both lines were alive, the results are even more conclusive. Forty-four lines attained more generations than the parent; four equalled the parent; and four completed a smaller number of fissions. Thus over eighty per cent. of the exconjugant lines attained more generations than their respective parent lines.