Cuvier, by founding the school of comparative anatomy, so furthered the knowledge of the organization of animals that he created an epoch.
Bichat, his great contemporary, created another by laying the foundation of our knowledge of the structure of animal tissues.
Von Baer, by his studies of the development of animal life, supplied what was lacking in the work of Cuvier and Bichat and originated modern embryology.
Haller, in the eighteenth, and Johannes Müller in the nineteenth century, so added to the ground work of Harvey that physiology was made an independent subject and was established on modern lines.
With Buffon, Erasmus Darwin,, and Lamarck began an epoch in evolutionary thought which had its culminating point in the work of Charles Darwin.
After Cuvier and Bichat came the establishing of the cell-theory, which created an epoch and influenced all further progress.
Finally, through the discovery of protoplasm and the recognition that it is the seat of all vital activity, arrived the epoch which brought us to the threshold of the biology of the present day.
Step by step naturalists have been led from the obvious and superficial facts about living organisms to the deep-lying basis of all vital manifestations.