In Pursuit of the Gene

56 ¨ GALTON’S DISCIPLES
accomplice who creates a diversion to help a charlatan.” In a letter to
Weldon the next day, he was only slightly more circumspect, writing, “It is
through things like this that I have come to doubt whether the world of
science is a school of truth or of deceiving.” 26
The following year, in June 1896, Bateson married, and Weldon, who
had once been his closest friend, was not invited to the reception. That October,
Bateson discovered what appeared to be a fatal flaw in Weldon’s
highly regarded experiments on selective death in Plymouth crabs. As he
explained it in a long letter addressed to Francis Galton in his capacity as
head of the Measurements Committee, which had sponsored Weldon’s
work, Weldon seemed to have overlooked an obvious confounding error. In
order to study the variability of shell dimensions as a function of age,
Weldon had grouped the crabs into seven groups according to size of shell.
However, it appeared that Weldon had failed to take into account the fact
that crabs molted in the course of development, sometimes shedding an
old shell and forming a new one as many as a dozen times before reaching
full adult size, and that individuals of the same size were not necessarily in
the same molt. Therefore, differences that Weldon attributed to differences
in age might in fact be due to differences in molting state. “It is so manifest
a difficulty that I cannot but think that it has already been considered
though no allusion is made to it in the Report,” Bateson wrote, with what
appeared to be genuine perplexity. 27
Galton’s first instinct was to brush aside Bateson’s objections, writing
back that he was “disposed towards a lenient view of special disturbing
causes in large collections of statistics, and on the other hand indisposed toward
too delicate handling of any statistics.” 28 Nonetheless, he agreed to
circulate Bateson’s letter among the other members of the committee.
Bateson wrote back the next day to say that it was evident from Galton’s response
that he had failed to make his point clear and asked if he might revise
his letter before it was circulated to the committee. “The difficulty,”
Bateson wrote, “is not overcome by reason of the extent of the collection of
statistics.” 29
On October 20, Bateson sent his revised critique to Galton, who sent it
on to Weldon, and two days later Galton received Weldon’s reply. “I quite