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History of Biology 343
became general among naturalists and systematists around 1900 (Karl Jordan, Edward
Poulton, David Starr Jordan). Shortly afterwards the saltationist views of the
geneticists Bateson and de Vries led to a deep schism between the experimentalists
on one hand and the naturalists on the other, which was only bridged by the evolutionary
synthesis during the 1930s and 1940s. Geographical isolation is now seen
as an important boundary condition for speciation to take place in conjunction
with natural selection and mutation rather than in competition with these factors
as some early pioneers had believed is the case.
The editor of the Harvard Library Bulletin, G. William Cottrell 1 ,suggested
to Mayr in 1958 that he prepare for this periodical a paper on Louis Agassiz
(1807–1873) who had been the founder and director of Harvard’s Museum of
Comparative Zoology and a lifelong opponent of Darwin (Mayr 1959c). Agassiz
was educated in Switzerland and Germany during a period that was dominated by
romantic ideas and by a largely metaphysical approach to nature, especially Plato’s
essentialism. Four main concepts determined his thinking: (1) A rational plan of
the universe, (2) typological thinking, (3) discontinuism, and (4) an ontogenetic
concept of evolution. The gradual change of one type (species) into another over
time was so inconceivable to Agassiz that it never entered his mind at all. It was
not religious scruples that prevented Agassiz from becoming an evolutionist but
rather a framework of ideas that could not be combined with evolutionism. Mayr
dedicated this paper to Erwin Stresemann on the occasion of his 70th birthday.
In 1970, after he had stepped down as Director of the Museum of Comparative
Zoology, Mayr began working on his history of ideas in biology (1982d), as
mentioned in his letters to Stresemann (“I am busy with my history of ideas in
biology,” 23 November 1970, and “I am working on a history of ideas in biology
and hope to have completed the manuscript until my retirement on 30 June 1975,”
26 December 1971). During the years of writing this large manuscript he published
several historical articles on Lamarck (1972f; discussed by Burkhardt 1994),
an essay review of books on the history of genetics (1973i), a historical survey
of American ornithology (1975c), and a brief review of the history of evolution
(1977f). In addition, Mayr contributed several articles to the growing “Darwin industry”
(see below) and organized, in 1974, two conferences to discuss the history
of the evolutionary synthesis.
In his review of the recent historiography of genetics (1973i), Mayr emphasized
the contributions of naturalist-systematists during the history of Mendelism and
population genetics, a subject which is dealt with again and in more detail in Mayr
(1982d).
As I mentioned above (p. 41), Erwin Stresemann in Berlin had been interested
in the history of ornithology since the 1910s and had published on and off in this
field. When, after 1945, other research was difficult because of political and logistic
postwar conditions, he turned his attention primarily to historical topics and
1 A major assistant in editing of the English translation of E. Stresemann’s Ornithology
from Aristotle to the Present (1975) and, during the 1980s, of the last volumes of Peters’
Check-list of Birds of the World.