| The first group consisted of 7 grains, normally developed of Triticum
similar type. The width-length index was approximately 1. All seeds germinated,
but only two of them survived in the early stage. The second group comprised 26 seeds, also with normally developed endosperm, but smaller and with a width-length index of approximately 1/2; on the whole they appeared to be of Aegilops type. The germination was poor, although all were swollen; 23 died off in the very early stage. Only 2 of 3 plants could be preserved and grown up. The third group consisted of grains with poor or without any endosperm, they were Aegilops-like in respect to colour and width-length index. After germination of nearly all grains had been initiated the majority died off. 10 of the strongest embryos were released from the seed-coat and cultivated in KNOP's solution with a supplement of 15% cane sugar. Cell divisions of all 10 embryos commenced but with irregularities regarding the number of primary roots and the differentiation in coleoptile and root. Only two of them could be grown up and the others remained in a vegetative stage without heading up to date. These F'2-hybrids exhibited characteristics of pure Aegilops, pure wheat and intermediate characteristics on the very same plant in mosaic-like pattern. The auricle, the expression of which is known not to be modified by environmental conditions, was observed over a longer period on all F'2-hybrids. It was observed that sometimes auricles of Aegilops and Triticum type not only change from stalk to stalk but also from sheath to sheath on the very same stalk. In addition to this some auricles appeared to be half-side Aegilops type and Triticum type. Similar somatic segregations could be also observed for other taxonomical characteristics, such as length of leaf and stalk, colour of nodes, hairing, etc. But these latter characteristics are too variable for proving the existence of a cytogenetical mosaic. Nevertheless, in the F2 a mosaic of characteristics corresponds with a mosaic of chromosome number. Further investigations not only of the mitosis but also of the meiosis of the F1 and F2 revealed besides the already described cytological mosaic further great deviations from the normal division in other respects, such as multipolar spindles, etc. |
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