The microscopic study of living organisms did not develop until the first half of the nineteenth century, in spite of earlier observation of “cells” by Robert Hooke (1665). It was only in 1831 that Robert Brown described a new structure in plant cells: the “nucleus.” In transferring microscopic observations of Mathias Schleiden on plant tissues (1838) to his own studies on animal tissues, Theodor Schwann (1839) made a major contribution by proposing the theory of universal cellular organization in living organisms. In this same year the Microscopical Society of London was founded, and among the founding members was James Scott Bowerbank.
In his paper, “On the structure of the shells of molluscan and conchyferous animals” (1844), Bowerbank showed that far from being simple aggregates of unorganized mineral particles, these shells are formed of sharply distinct units, each possessing a definite geometry whose regular arrangement demonstrates that their order is completely controlled by the producing organism. The rapid diffusion of this new type of analysis is attested to by the publication the following year of Carpenter's paper, “On the microscopic structure of shells” (1845, with a second part in 1847).