Histology mounts are often what comes to mind for many people when "old microscope slides" are mentioned. Without doubt, our knowledge of the human body's structures and processes, as well of those of animals and plants,  owes a great deal to the early slide makers of the Victorian era. Before about 1840, all mounted histology specimens were thick sections of tissue, sometimes injected with various substances to make the structures more visible, and usually mounted as "deep cell" fluid mounts (see top row, 2nd from left - engraved "Skin from the Ear of the Cat showing the Vessels of the bulbs, & the hairs   Hett, 1849" ). These thick preparations could only be examined microscopically with reflected (incident) top lighting, and provided limited information. The early commercial slide preparers such as C. M. Topping, J. T. Norman, A. C. Cole, and E. Wheeler  often worked closely with the leading medical professionals of the era to further current research and knowledge in the fields of medicine and surgery. These individuals, by their dedicated efforts, helped develop the techniques in preparation and preservation that allowed the research that underlies the remarkable advances in medicine that we benefit from today. An important early development was consistent thin sectioning of tissue specimens, and preparation/preservation techniques that enabled use of transmitted (through the specimen) lighting. This advance allowed microscopic examination of the minute structures, helping open the door to a better understanding of the processes of disease, and the development of new effective treatments. A wide variety of histology mounts were prepared by most of the more capable preparers, covering all the major tissue types (both healthy and diseased) of both human and animal species.