In the period 1875-1920, a debate about the generality and applicability of evolutionary theory to all organisms was motivated by work on unicellular ciliates like Paramecium because of their peculiar nuclear dualism and life cycles. The French cytologist Emile Maupas and the German zoologist August Weismann argued in the 1880s about the evolutionary origins and functions of sex (which in the ciliates is not linked to reproduction), and death (which appeared to be the inevitable fate of lineages denied sexual conjugation), (...) an argument rooted in the question of whether the ciliates and their processes where homologous to other cellular organisms. In the beginning of the twentieth century, this question of homology came to be less important as the ciliates were used by the British protozoologist Clifford Dobell and the American zoologist Herbert Spencer Jennings to study evolutionary processes in general rather than problems of development and cytology. For them, homology mattered less than analogy. This story illustrates two partially distinct problems in evolutionary biology: first, the question of whether all living things have common features and origins; and second, whether their history and current nature can be described by identical mechanisms. Where Maupas (contra Weismann) made the ciliates qualitatively the same as all other organisms in order to create a cohesive evolutionary theory for biology, Jennings and Dobell made them qualitatively different in order to achieve the same end. (shrink)

The ArgumentThe popularity of botany and natural history in England combined with the demographic changes of the first half of the nineteenth century to bring about a new aesthetics of gardening, fusing horticultural practice with a connoisseurship of botanical science. Horticultural societies brought theoretical botany into the practice of gardening. Botanical and horticultural periodicals disseminated both science and prescriptions for practice, yoking them to a progressive social agenda, including the betterment of the working class and urban planning. Finally, botany was (...) incorporated into systems of education, reinforcing the union of theory and practice.Three garden plans from the 1790s, 1835, and 1846 illustrate the embodiment of this theory and practice in the design of private suburban gardens. These horticultural/botanical gardens, described in the second half of the article, represent a neglected side of botany's bifurcated descent from Renaissance collections of curiosities into horticultural gardening and herbarium-based systematics. (shrink)