From Plant Breeding to Heredity. Clones and Pure Lines

Christina Brandt, Max Planck Institute for the History of Science, Berlin

Abstract
Session title: Genealogy, Pure Lines, and Radiation. Towards a Cultural History of Classical Genetics

From plant breeding to heredity. Clones and pure lines.
This paper will examine one chapter of the early history of the clone and cloning. The paper addresses the emergence of the clone as a technical object in two different experimental systems during the first two decades of the 20th century.
Like the concept of the gene, the concept of the clone was first introduced to biology at the beginning of the 20th century. Whereas the gene concept referred to an abstract or even ideal unit (according to Wilhelm Johannsen’s use of the term) the concept of the clone, on the other hand, from the beginning referred to a concrete material object. In 1903 Herbert J. Webber, a botanist from the Plant Breeding Laboratory of the US Department of Agriculture introduced the term “clone” to designate “groups of plants that are propagated by the use of any form of vegetative parts (....) and which are simply parts of the same individual seedling.”
Though the concept was first developed in the context of horticultural breeding, the clone soon became something which could be called a technical object of different experimental systems in the first decades of the 20th century. In this paper, I will analyze the use of clones and of clonal techniques in the field of cell biology. The focus will be on the work of V. Jollos in the 1910s and on the work of Joachim Haemmerling in the 1920s. Both scientists were coworkers of Max Hartmann at the KWI for Biology in Berlin Dahlem.
In 1916, V. Jollos performed experiments on the influence of temperature and poison on “pure lines” of Paramaecium caudatum, which he designated “clones”; the context of this research was the debate about the inheritance of experimentally generated modifications. Thus, the clone concept was used synonymously with the concept of a „pure line“, which was introduced originally by Wilhelm Johannsen in 1903. Johannsen had defined “pure lines” as individuals (plants) that descended from a single self-fertilizing individual. These “pure lines” were the experimental material that led Johannsen to differentiate between phenotype and genotype, and hence to the introduction of the gene concept.
In the 1920s, other clones were used for cytological work: Joachim Haemmerling (who later became very well known for his research on cell nuclei transplantation in Acetabularia) worked on a clone of a very simple worm (Aelosoma hemprichii). In a broader context, Haemmerling´s research was related to questions concerning (cell) aging and death as well as the role of asexual propagation and its presumed rejuvenating effect on the organism. The paper will discuss these two cytological research lines against the broader background of emerging theories of heredity and reproduction.

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