In Pursuit of the Gene

CHAPTER 8
Cell Biology
¨ THE PRODUCT OF AN ASTONISHING clarity of thought and analytic
penetration, Mendel’s abstract system of heredity had seemed entirely
ungrounded to his contemporaries. In fact it would take four decades of intensive
investigation of the cell, the nucleus, and its contents to discover
that there were physical entities in the nucleus, the chromosomes, that behaved
exactly as Mendel’s theory predicted they should. Unlike Mendel’s
solitary effort, the development of an understanding of the material basis of
heredity was a vast communal effort that drew on the insights and observations
of many investigators in Europe and later in America.
The new understanding of the cellular basis of life began in Germany
in the 1840s, with the recognition by Theodor Schwann and Matthias J.
Schleiden that cells were the fundamental building blocks of life and that
each cell contained a nucleus. Although the Schleiden-Schwann cell theory,
as it would come to be known, was a major advance, both Schwann