In Pursuit of the Gene

X-RAYS © 237
birth of the baby, while Jessie recovered in the hospital, Muller began to
think in earnest about the radium experiments. Several people had made
similar attempts with varying degrees of success, beginning with Morgan,
who had, following a suggestion of De Vries, tried to induce mutations
with radium around 1910 and succeeded in isolating the beaded and truncate
mutants. But with the flood of new visible mutants and results, Morgan
hadn’t felt the need to continue treating flies with radium.
Starting in 1917 a former Morgan student, Harold Plough, had also
experimented with the effects of radium on flies and had found that radium
exposure increased the rate of crossing over between chromosomes,
but Muller thought Plough’s experiments were poorly designed and the results
in his recently published paper were internally inconsistent. 50 Plough’s
work had been followed up by Mavor, a radiologist at Union College in
Schenectady, who found that machine-produced X-rays also worked to accelerate
the rate of exchange between chromosomes, 51 but neither Plough
nor Mavor was focused on the mutation problem. “The field here is still
open,” Muller wrote Altenburg, brimming over with confidence. 52
After settling on an experimental plan, Muller invited Altenburg to
visit Jessie, David, and himself for Thanksgiving, when they could complete
the experiment. He also planned to do an independent study to test the effect
of machine-produced X-rays at the same time, but “of course,” he assured
Altenburg, “if you want to do it with Ra. [radium] I’ll do that with
you first.” 53
Altenburg’s visit had to be postponed after Jessie began to have difficulty
with breast-feeding the new baby, who was being fed seven times a
day on artificially pumped breast milk delivered by spoon in order that he
not “mis-learn to suck human nipples thru the differently constructed
bottle nipples.” 54 Consumed by the demands of the new baby and his
teaching, Muller was forced to abandon his fly crosses for several months,
and in the spring of 1925 Altenburg fell ill with severe stiffness in his back,
which would later be diagnosed as ankylosing spondylitis. With Altenburg’s
illness the radium experiments appear to have been put on hold, and in
the meantime Muller began experimenting with machine-produced X-rays.