An analysis of the effect of varying the duration of X-ray treatment upon the frequency of mutations

The X-ray has become an instrument adaptable to the needs of the investigator in the study of his genetic problems. Previously to Muller's discovery that the germ plasm could be modified by the use of radiation, geneticists had to follow the slow process of awaiting the spontaneous origination of the variations that they needed for their investigations. Now, however, they can produce variations in numbers sufficiently great to meet their needs; but they cannot as yet, at least, produce mutations at a definite desired locus or of a definite desired type. If we intend to use the X-rays as a tool with which to work, we must learn the best methods to be employed in the handling of that instrument. It is necessary to find out what possibilities may be expected when the conditions under which the tool is used are modified. If possible, we must separate the different kinds of resulting genetic variants from each other, and determine whether, by variation in our method, we can obtain variation in the types of mutations so marked that the different genetic effects will be distinctly separated