In Pursuit of the Gene

CELL BIOLOGY © 153
whose lifetime ambition was to establish the facts of heredity experimentally.
The 22-year-old Boveri began work in Richard Hertwig’s Zoological
Institute in Munich in 1885, just at the moment when the idea that the hereditary
material was located in the as-yet-unnamed chromosomes began
to gain currency. Through Hertwig, Boveri received the ideal introduction
to cytology, and in particular to the study of the nucleus, which was rapidly
becoming a subfield of its own. Deeply impressed by van Beneden’s results,
Boveri spent his first several years in Hertwig’s institute repeating van
Beneden’s work on egg cell formation in Ascaris. 25 In January 1888, Boveri
visited Naples, where as fate would have it he was a guest in the same
pensione where Weismann was staying.
Although few men were better prepared than Boveri to accept Weismann’s
views on the role of the reduction division in the formation of sex
cells, Boveri and Weismann had a fundamental disagreement over the nature
of the chromosomes. Whereas Weismann believed that the chromosomes
were all essentially identical, each containing multiple copies of “ancestral
germ-plasms,” Boveri’s work on the chromosomes in the egg cells of
Ascari had convinced him that the individual chromosomes differed in form
and function, and each evening after returning from the Zoological Station
the two men argued. 26 That spring, Boveri began to collect a variety of marine
forms from the Sea of Naples and made detailed renderings of carefully
prepared chromosome arrays isolated from their sex cells, documenting
the differences in the sizes and shapes of the individual chromosomes, as
well as the way they changed from one generation to the next. He soon
found that in each case the sperm and egg cells contained identical sets of
chromosomes; 27 this was consistent with the idea that the chromosomes are
the repository of the hereditary material, but it did not yet constitute a
proof. 28
Boveri continued the work on chromosomes when he returned to Munich
in April 1888, and later the same year he presented the fruits of this
new line of inquiry in the second of six “Cell Studies,” a unique amalgam of
genetics, cytology, and embryology that immediately established him as a
world leader in the study of heredity. In this paper Boveri clearly showed
that the chromosomes, which disappeared during the resting period be-