Experimentalists and naturalists in twentieth-century botany: Experimental taxonomy, 1920?1950
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Julian Huxley, Evolution: The Modern Synthesis (London: Allen and Unwin, 1942).
The Modern Synthesis as a unifying force in twentieth-century biology is a general theme of all the essays in Ernst Mayr and William B. Provine, eds., The Evolutionary Synthesis (Cambridge, Mass.: Harvard University Press, 1980).
This interpretation is comprehensively presented by Ernst Mayr in two articles, ?Prologue: Some Thoughts on the History of the Evolutionary Synthesis? and ?The Role of Systematics in the Evolutionary Synthesis,? both of which appear in Mayr and Provine, The Evolutionary Synthesis. Garland Allen mentions ?the longstanding separation and distrust between laboratory and field workers? in his Life Science in the Twentieth Century (New York: Wiley, 1975), p. 19. A somewhat similar distinction between ?orthodox? and ?experimental? taxonomists is presented by John Dean, ?Controversy over Classification: A Case Study in the History of Botany,? in Natural Order: Historical Studies in Scientific Culture Barry Barnes and Steven Shapin ed. (Beverly Hills, Calif.: Sage, 1979).
Mayr, ?Prologue,? p. 13.
Ibid., p. 40?42.
I shall use the term ?experimental taxonomy,? since it appears to have enjoyed wide currency between 1920 and 1950. It was used as a general descriptive term referring to the use of cytological, ecological, and genetic methods for the study of systematic relationships among plants. In referring to specific botanists as experimental taxonomists, I am not necessarily implying that they themselves claimed the designation; rather, I am suggesting that they shared a particular methodology and a loose set of common objectives.
Frederic E. Clements, Research Methods in Ecology (Lincoln, Nebr.: University Publishing Co., 1905), pp. 12?13.
F. E. Clements and H. M. Hall, ?Experimental Taxonomy,? Carnegie Inst. Wash. Yearb., 18 (1919), 334?335.
Anton Kernervon Marilaun, The Natural History of Plants, trans. F. W. Oliver (New York: Holt, 1895), pt. 2, p. 514. Emphasis in original.
Bonnier's experiments were flawed by methodological problems. What he claimed to be transformed lowland species may well have been related alpine species that had invaded the experimental garden. A critical analysis of Bonnier's research is provided by William M. Hiesey, ?Environmental Influence and Transplant Experiments,? Bot. Rev., 6 (1940), 181?203.
Aside from brief accounts published in Carnegie Institution of Washington Yearbook beginning in 1918, Clements' only discussion of experimental speciation was in an article devoted primarily to experimental methodology. In the paper he deferred detailed discussion to a later report ? which was, however, never published. See Frederic Clements, ?Experimental Methods in Adaptation and Morphogeny,? J. Ecol., 17 (1929), 357?379.
Clements' experiments probably were marred by the same methodological problems encountered by Bonnier. Hall and his associates were unable to confirm any of Clements' experimental results. See Hiesey, ?Environmental Influence,? pp. 185?187.
Göte Turesson, ?The Genotypical Response of the Plant Species to the Habitat,? Hereditas, 3 (1922), 211?347. I have discussed the development of Turesson's ideas in greater detail in ?Experimental Taxonomy, 1930?1950: The Impact of Cytology, Ecology, and Genetics on Ideas of Biological Classification? (Ph.D. diss., Oregon State University, 1982).
J. W. Gregor, ?The Units of Experimental Taxonomy,? Chron. Bot., 7 (1942), 193?196; D. H. Valentine, ?The Units of Experimental Taxonomy?, Acta Biotheoret., 9 (1949), 75?88.
The term ?genecology? was coined by Turesson to refer to the ecological study of species. Genecology later became associated with ecological genetics. However, in his early writings Turesson made a clear distinction between genetics and ecology. See Göte Turesson, ?The Scope and Import of Genecology,? Hereditas, 4 (1923), 171?176.
Turesson's system was one of several nomenclatorial reforms proposed by experimental taxonomists. For a detailed discussion see Hagen, ?Experimental Taxonomy.?
Harvey Monroe Hall and Frederic E. Clements, ?The Phylogenetic Method in Taxonomy,? Carnegie Inst. Wash. Publ. no 326 (1923).
Although methodologically traditional, the monograph was controversial because Hall and Clements ?lumped? a larger number of species into a few comprehensive ones. This was a direct attack on the earlier work of P. A. Rydberg, who responded to Hall and Clements in ?Scylla and Charybdis,? Proc. Internat. Cong. Plant Sci. (1926), 1539?51.
The results of two decades of transplant experiments were compiled in Jens Clausen, David D. Keck, and William M. Hiesey, ?Experimental Studies on the Nature of Species. I. Effect of Varied Environments on Western North American Plants,? Carnegie Inst. Wash. Publ. no. 520 (1940).
H. M. Hall, ?Heredity and Environment-as Illustrated by Transplant Studies,? Sci. Monthly, 35 (1932), 289?302.
H. M. Hall, ?Significance of Taxonomic Units and Their Natural Basis from the Point of View of Taxonomy,? Proc. Internat. Cong. Plant Sci. (1926), 1571?74.
Although Hall may have had little sympathy for Clements' evolutionary views, he shared Clements' fundamental assumptions about taxonomy. Both men favored grouping small species, both supported an explicitly phylogenetic basis for classification, and both argued that the use of experimental methods would make classification more ?objective?.
Hall, ?Significance of Taxonomic Units.?
Ibid.
H. M. Hall, ?Letter to Carlotta Case Hall-August 21, 1926,? H. M. Hall papers, University of California, Berkeley, Bancroft Library.
George H. Shull, ?Significance of Taxonomic Units and Their Natural Basis: Point of View of Genetics,? Proc. Internat. Cong. Plant Sci. (1926), 1578?86. Emphasis in original.
K. M. Wiegand, ?Discussion of Dr. H. M. Hall's Paper,? Proc. Internat. Cong. Plant Sci. (1926), 1575?76.
Ernest Brown Babcock and Harvey Monroe Hall, ?Hemizonia congesta, A Genetic, Ecologic, and Taxonomic Study of the Hay-Field Tarweeds,? Univ. Cal. Publ. Bot., 13 (1924), 15?100.
E. B. Babcock, ?Investigations in the Genus Crepis,? Carnegie Inst. Wash. Yearb., 25 (1926), 316?317.
Ernest Brown Babcock, ?The Genus Crepis,? Univ. Cal. Publ. Bot., 21, 22 (1947), 1?1030.
G. Ledyard Stebbins, ?Ernest Brown Babcock?, Biog. Mem. Nat. Acad. Sci., 32 (1968), 50?66.
According to Stebbins, Clausen hired Keck and Hiesey after Hall's death. See Stebbins' ?Botany and the Synthetic Theory of Evolution? in Mayr and Provine, The Evolutionary Synthesis. However, Keck and Hiesey were coauthors with Hall on research reports dating back to 1927, four years before Clausen joined the group. See ?Experimental Taxonomy?, Carnegie Inst. Wash. Yearb., 26 (1927), 311?312.
Stebbins, ?Botany and the Synthetic Theory,? notes Clausen's frequent correspondence with the Scottish botanist J. W. Gregor. In response to my questions on this matter, David Keck suggested the importance of Clausen's correspondence with European botanists.
Among the prominent early members of the biosystematists were E. B. Babcock, Jens Clausen, Lincoln Constance, Richard Goldschmidt, William Hiesey, David Keck, Herbert Mason, and G. Ledyard Stebbins. When questioned, Constance, Hiesey, Keck, and Stebbins all remarked on the usefulness of this discussion forum.
Perhaps the major contribution of this group was the publication of a widely read set of essays: Julian Huxley, ed., The New Systematics (London: Oxford University Press, 1940). In addition, the group sponsored several symposia on the relation of taxonomy to various other disciplines.
Ibid.
W. B. Turrill, ?The Expansion of Taxonomy with Special Reference to Spermatophyta,? Biol. Rev., 13 (1938), 342?373.
G. Ledyard StebbinsJr., ?The Significance of Polyploidy in Plant Evolution,? Amer. Nat., 74 (1940), 54?66.
Dean, ?Controversy over Classification,? cites a number of these conflicts as evidence for a dichotomy between herbarium taxonomists and experimental taxonomists.
A. J. Wilmott, ?Experimental Delimitation of Species?, J. Bot., 70 (1932), 49?50.
Ibid.
J. W. Gregor, ?Correspondence?, J. Bot., 70 (1932), 154?155; A. J. Wilmott, ?Correspondence?, ibid., 155.
Indeed, during the two decades following 1931 cytogeneticists demonstrated that the relationships among polyploid groups in Phleum were considerabley more complex than Gregor had proposed. For a brief discussion of cytogenetic research on Phleum see G. Ledyard StebbinsJr., Variation and Evolution in Plants (New York: Columbia University Press, 1950), p. 333.
C. D. Darlington, Recent Advances in Cytology (Philadelphia: Blakiston's 1932). For brief discussions of the reception of Darlington's text see Hampton Carson, ?Cytogenetics and the Neo-Darwinian Synthesis?, and C. D. Darlington, ?The Evolution of Genetic Systems: Contributions of Cytology to Evolutionary Theory?, both in Mayr and Provine, The Evolutionary Synthesis.
For example, in a presidential address to the American Society of Plant Taxonomists, W. H. Camp noted: ?Our present system of nomenclature was designed to fit a concept of static genera and species. Tinker with it as we will, we cannot re-tailor this mouldy shroud into something which will serve as an adequate nomenclatural covering for the complex, living groups which we are now beginning to realize must be defined?. See W. H. Camp, ?Biosystematy?, Brittonia, 7 (1951), 113?127.
Gregor, in ?Units of Experimental Taxonomy?, noted that while they were basically different, experimental taxonomy and orthodox taxonomy were ?mutually helpful?.
Statistical analysis cannot be considered merely an adjunct to experimental biology. Indeed, it appears that field biologists and taxonomists were among the leading advocates of statistical methods. This was true of zoologists as well as botanists. For example, G. C. Robson and O. W. Richards reviewed numerous examples of statistical field studies (?population analysis?) in The Variation of Animals in Nature (London: Longmans, 1936), p. 15. Similar suggestions for combining statistics and taxonomy are found in Edgar Anderson and W. B. Turrill, ?Biometrical Studies on Herbarium Material?, Nature, 136 (1935), 986.
E. B. Babcock and G. L. Stebbins, Jr., ?The American Species of Crepis ? Their Interrelationships and Distribution as Affected by Polyploidy and Apomixis?, Carnegie Inst. Wash. Publ. no. 504 (1938).
Hall, ?Heredity and Environment?.
J. Heslop-Harrison, New Concepts in Flowering-Plant Taxonomy (London: Heinemann, 1953), p. 122.