In Pursuit of the Gene

VIVA PANGENESIS © 13
tions of pangenesis, writing instead, “I want to make some peculiar experiments
that have occurred to me in breeding animals and want to procure a
few couples of marked and assured breeds.” 43 As an afterthought, seemingly
intended to pique Darwin’s interest, he added, “Pray excuse my troubling
you; the interest of the proposed experiment—for it really is a curious
one—must be my justification.”
Galton’s experiment was designed to test for the presence of circulating
particles that carried hereditary information. Circulation of the particles was
the key to the inheritance of acquired traits, for circulating particles were
required to transmit changes in one part of the body (neurons, for example)
to distant reproductive cells. The ubiquitous gemmules ought certainly
be found in the blood of mammals, Galton reasoned, and thus it
ought to be possible to transfer the gemmules from one animal to another
by performing a blood transfusion. In particular, Galton proposed to transfuse
blood from mongrel rabbits into pure breeds. If the theory were correct,
one would expect pure-bred rabbits containing mongrel gemmules to
give rise to mongrel progeny. A positive finding would go a long way toward
establishing the existence of circulating gemmules and their role in
inheritance. A negative finding, on the other hand, would constitute a near
fatal blow to pangenesis. For if blood did not contain gemmules, then it
seemed reasonable to conclude that cells of the body were not actively
shedding them, and then there was no longer a mechanism by which to
transmit acquired traits.
Darwin’s assistance to Galton would be invaluable: Not only was Darwin
a compendium of information about the various breeds of rabbits (and
virtually any other animal or plant), but he had a network of relationships
with animal breeders throughout England. However, it wasn’t Darwin’s
connections or his vast knowledge of the natural world that would be most
helpful to Galton. Galton was lifted up by his connection to the great man
himself. The fact that Darwin had been intoxicated by his initial reading of
Hereditary Genius meant the world to him. Forsaking his usual reserve, Darwin
had written on December 23, 1869: “I have only read 50 pages of your
Book, but I must exhale myself, else something will go wrong in my inside.
I do not think I ever in all my life read anything more interesting and origi-