Infusorians, Algae, Zoophytes

Simple organisms were at the center of experimental natural histories at the turn of the nineteenth century. Animacules appeared in infusion experiments; investigations of polyps demonstrated the properties of both plants and animals; the translucent structure and rapid proliferation of algae made visible the formative drive of life. The empirical study of infusorians, zoophytes, and algae stimulated reimaginings of natural history. They drew attention not only to the variability of organic life but also to its connections to the physical world, and prospects of its transgressive modes of propagation, transformation, and even spontaneous generation. These simple forms of life were media which provided occasions for remarkable encounters with the agency of life. They also gave rise to fictive experiments in natural history, speculative renderings of the history of life and its implications for human life. Such humble organisms played an outsized role in the development of an experimental natural history, both empirical and speculative, from Buffon and Tremblay, through Diderot and Erasmus Darwin, to Lamarck and Treviranus.