"That plants and animals are composed of cells was not revealed until the invention of the microscope, which although very rude in its construction and efficiency as compared with microscopes of today, was beginning to be employed by Robert Hooke (1635-1703) and others in the seventeenth century in the study of plants. Robert Hooke, one of the earliest to study plants with the microscope, examined thin sections of cork, and found the cork to be composed of numerous small compartments which he called cells on account of their rough resemblance to the cells of a honeycomb."