(1) By the irradiation of X-ray on the young shoots in
Trifolium repens, morphological abnormalities are always observed in the leaves developing from the treated shoot. Also, there are always some of cytological abnormalities of mitotic figures in the root tip which develops from each of nodes bearing the abnormal leaves.
(2) The abnormalities of leaves represent a high degree of the variability in form and size.
(3) It may be assumed that a parallel relationship exists between the degree of abnormalities of leaves and the frequency of abnormality of the mitotic chromosome in the root tip.
(4) In the root tip, when the abnormal mitosis occurrs of more than about 5 percent in frequency, the shoot was dead, or stopped its further development.
(5) It may be concluded with certainty that a morphological change of abnormal leaves should be recognized definitely in the course of recovering, directly proportional to decreasing of the abnormal mitosis, as follows:
+
D→+inc→+P→+mal→+ab→normal
(6) When a complete recovering of the abnormal leaves to the normal ones occurs, abnormal mitosis is observed in most of such shoots. In spite of the healing of abnormalities of mitosis, the constant abnormalities of leaves were however observed in only two cases, one of which was designated to be “
E Cri WR or
Ecri W
W W
W” and other to be “
ab”. Those two constant abnormal types in the leaves may be considered to be a gene mutation induced by X-ray irradiation.
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