Excerpt: ...and this was chosen for closer experiments. In the year of 1888 I had the good luck to isolate some syncotylous seedlings and of finding among them one with 19% of inheritors among its seeds. The following generation at once surpassed the ordinary average and came up in three individuals to 76, 81 and even 89%. My race was at once isolated and ameliorated by selection. I have tried to improve it further and selected the parents with the highest percentages during seven more generations; but without any ...
Read More
Excerpt: ...and this was chosen for closer experiments. In the year of 1888 I had the good luck to isolate some syncotylous seedlings and of finding among them one with 19% of inheritors among its seeds. The following generation at once surpassed the ordinary average and came up in three individuals to 76, 81 and even 89%. My race was at once isolated and ameliorated by selection. I have tried to improve it further and selected the parents with the highest percentages during seven more generations; but without any remarkable result. I got figures of 90% and above, coming even in one instance up to the apparent purity of 100%. These, however, always remained extremes, the averages fluctuating yearly between 80-90% or thereabouts, and the other extremes going nearly every year downwards to 50%, the value which would be attained, if no selection were made. Contra-selection is as easily made as normal selection. According to our present principle it means the choice of the parents with the smallest hereditary percentage. One might easily imagine that by this means the dicotylous seedlings could be rendered pure. This, however, 426 is not at all the case. It is easy to return from so highly selected figures as for instance 95% to the average about of 50%, as regression to mediocrity is always an easy matter. But to transgress this average on the lower side seems to be as difficult as it is on the upper side. I continued the experiment during four succeeding generations, but was not able to go lower than about 10%, and could not even exclude the high figures from my strain. Parents with 65-75% of syncotylous seedlings returned in each generation, notwithstanding the most careful contra-selection. The attribute is inherent in the race, and is not to be eliminated by so simple a means as selection, nor even by a selection on the ground of hereditary percentages. We have dealt with torsions and fasciations and with seedling variations at some length, in order to point...
Read Less