occurred in this generation was almost exactly three times as great as the number of the dwarfs. As in the previous year, seed were carefully collected from this, the second hybrid generation, and in every case _the seeds from each individual plant were harvested separately and separately sown in the following year_. By this respect for the individuality of the different plants, however closely they resembled one another, Mendel found the clue that had eluded the efforts of all his predecessors. The seeds collected from the dwarf recessives bred true, giving nothing but dwarfs. And this was true for every dwarf tested. But with the talls it was quite otherwise. Although indistinguishable in appearance, some of them bred true, while others behaved like the original tall hybrids, giving a generation consisting of talls and dwarfs in the proportion of three of {20} the former to one of the latter. Counting showed that the number of the talls which gave dwarfs was double that of the talls which bred true. T x D --------------------- P | T(D) --------------------- F_1 | +-----------+-----------+-------------+ T T(D) T(D) D --- F_2 | +---+----+--+ +--+----+---+ | T T T(D) T(D) D T T(D) T(D) D D --- F_3 | | T D --- F_4 If we denote a dwarf plant as D, a true breeding tall plant as T, and a tall which gives both talls and dwarfs in the ratio 3 : 1 as T(D), the result of these experiments may be briefly summarised in the foregoing scheme.[2]