Abstract
The experiments to be described were performed with a view to determining if x-rays by affecting the x-chromosome could disturb the inheritance of a sex-linked character. Wild type (red-eyed) females of Drosophila melanogaster, homozygous for red-eye were x-rayed soon after emerging from the pupa with a dose just under the sterilization dose and mated to white-eyed males. The white-eyed character being recessive to the red-eyed the normal result of crossing a homezygous red-eyed female with a white-eyed male is for the offspring in the first generation to be all red-eyed if there is no non-disjunction.
In all, four experiments have been completed to date. In three of these thirty-five virgin females, homozygous for the red-eyed character, were mated with white-eyed males. Nineteen of these were used as controls and sixteen were x-rayed soon after emerging from the pupa and immediately before mating. The rayed females were the sisters of the controls. None of the nineteen control pairs produced white-eyed males. One of the rayed females was sterile. Of the fifteen fertile, rayed females, twelve produced one or more white-eyed males.
In two of the four experiments the white-eyed males which were crossed with the rayed females were also homozygous for dumpy, a second chromosome character. All of the six exceptional males produced had normal wings with the exception of one which died before its wings expanded. It therefore seems probable that only the x-chromosome was affected.
Further experiments using multiple sex-linked stock, eosin miniature and scute-echinus-cut-vermilion-garnet-forked, have shown that probably the whole x-chromosome is affected.
Since the eggs which produced the exceptional males were laid during the first six days after raying it seems reasonable to believe that they were acted upon while in or preparing for one of the maturation divisions.
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