Embryo Project Encyclopedia

Frank R. Lillie was born in Toronto, Canada, on 27 June 1870. His mother was Emily Ann Rattray and his father was George Waddell Little, an accountant and co-owner of a wholesale drug company. While in high school Lillie took up interests in entomology and paleontology but went to the University of Toronto with the aim of studying ministry. He slowly became disillusioned with this career choice and decided to major in the natural sciences. It was during his senior year that he developed his lifelong interest in embryology. Graduating with a BA in 1891 Lillie then moved to the Marine Biological Laboratory (MBL) at Woods Hole, Massachusetts, to work and study with Charles Otis Whitman, the founding director of the MBL. Lillie collected and studied cell lineage side-by-side with some of the most prominent embryologists of the time: Edmund B. Wilson, Edwin G. Conklin, and Aaron L. Treadwell. Along with his cell lineage studies, Whitman guided Lillie to work on the question of how blastomeres contributed to the formation of organs in fresh water clams.

Ernest Everett Just was an early twentieth century American experimental embryologist involved in research at the Marine Biological Laboratory (MBL) at Woods Hole, Massachusetts, and the Stazione Zoologica in Naples, Italy. Just was known for simple but elegant experiments that supported the "fertilizing" theory of Frank R. Lillie and served as an antagonist to Jacques Loeb's work with artificial parthenogenesis. Just's many experiments with marine invertebrates showed that the egg surface, or ectoplasm, plays an important role in the fertilization and development of eggs.

Anatomical models have always been a mainstay of descriptive embryology. As the training of embryologists grew in the late 1800s, so too did the need for large-scale teaching models. Embryo wax models, such as those made by Adolf Ziegler and Gustav Born, were popular in the latter part of the nineteenth century and the early twentieth century as a way to visualize, in three dimensions, the fine detail of embryos without the aid of a microscope. While these models were found in many university laboratories, museums of science, and even expositions and world's fairs, they were anything but easy to make or obtain. Wax modeling required skill, patience, and specialized tools. Small laboratories with only one or two embryologists often found the prospect of wax modeling too laborious, too difficult, and too expensive to make the pursuit worthwhile. As an alternative, Susanna Phelps Gage, an embryologist at Cornell University, perfected a technique of using stacks of absorbent blotting paper rather than stacks of wax plates for constructing embryo models. She first demonstrated her blotting paper method to other embryologists at the annual meeting of the Association of American Anatomists in 1905 and later at the International Zoological Congress, held in Boston in August 1907.

Hans Spemann was an experimental embryologist best known for his transplantation studies and as the originator of the "organizer" concept. One of his earliest experiments involved constricting the blastomeres of a fertilized salamander egg with a noose of fine baby hair, resulting in a partially double embryo with two heads and one tail. Spemann continued changing variables such as the amount of time the embryo was constricted and the degree of constriction, all of which added more empirical evidence to Hans Driesch's studies showing that embryonic cells could self-regulate to varying degrees. Spemann's long list of "simple" experiments and significant findings were mainly carried out at his laboratory, the Spemann School at the University of Freiburg, Germany, where numerous graduate students collaborated with Spemann to investigate embryonic induction.

Historically the exact age of human embryo specimens has long perplexed embryologists. With the menstrual history of the mother often unknown or not exact, and the premenstrual and postmenstrual phases varying considerably among women, age sometimes came down to a best guess based on the weight and size of the embryo. Wilhelm His was one of the first to write comparative descriptions of human embryos in the late 1800s. Soon afterward, Franklin P. Mall, the first director of the Carnegie Institution of Washington's (CIW) Department of Embryology, expanded upon His' work. Mall's first efforts were to place embryos into stages based on menstrual ages and body length. This method ran into problems however when it became apparent that obtaining menstrual ages was often impossible or simply too inaccurate even if the information could be obtained from the women who carried the embryos. Mall decided instead to look for patterns among embryos to come up with some type of staging system whereby embryo age could be more accurately determined.

Jacques Loeb is best known for his embryological work investigating parthenogenesis in invertebrates. Artificial Parthenogenesis and Fertilization is a revised and English-translated work from his earlier book, Die chemische Entwicklungserregung des tierischen Eies (1900). Artificial Parthenogenesis describes Loeb's many and varied methodical experiments to initiate egg development without fertilization by sperm. As is true with much of science, some of Loeb's experiments were successful and many were not. Artificial Parthenogenesis presents a sense of what early twentieth century embryology looked like: experimenters' overarching desire for manipulation and control, coupled with their use of chemicals and macromolecules as agents of change. The book also illuminates the historical role of the sea urchin in the study of embryological development.

Stephen Jay Gould studied snail fossils and worked at Harvard University in Cambridge, Massachusetts during the latter half of the twentieth century. He contributed to philosophical, historical, and scientific ideas in paleontology, evolutionary theory, and developmental biology. Gould, with Niles Eldredge, proposed the theory of punctuated equilibrium, a view of evolution by which species undergo long periods of stasis followed by rapid changes over relatively short periods instead of continually accumulating slow changes over millions of years. In his 1977 book, Ontogeny and Phylogeny, Gould reconstructed a history of developmental biology and stressed the importance of development to evolutionary biology. In a 1979 paper coauthored with Richard Lewontin, Gould and Lewonitn criticized many evolutionary bioligists for relying solely on adaptive evolution as an explanation for morphological change, and for failing to consider other explanations, such as developmental constraints.

Felix Anton Dohrn is best remembered as the founder of the Stazione Zoologica di Napoli, the world' s first permanent laboratory devoted to the study of marine organisms. Dohrn was born on 29 December 1840 in Stettin, Pomerania (now Poland), to a wealthy merchant family. Dohrn's paternal grandfather, Heinrich, trained as a surgeon and then established a sugar refinery, while Dohrn's father, Carl August Dohrn, who inherited the family business, became interested in natural history through Alexander von Humboldt, a family friend. Once settled in his career, Anton Dohrn's own research never strayed far from the origin of vertebrates. He promoted the theory that vertebrates closely resemble and are derived from annelid-like ancestors and he spent years studying the early embryogenesis of lower vertebrates in attempts to prove this.

Aristotle studied developing organisms, among other things, in ancient Greece, and his writings shaped Western philosophy and natural science for greater than two thousand years. He spent much of his life in Greece and studied with Plato at Plato's Academy in Athens, where he later established his own school called the Lyceum. Aristotle wrote greater than 150 treatises on subjects ranging from aesthetics, politics, ethics, and natural philosophy, which include physics and biology. Less than fifty of Aristotle's treatises persisted into the twenty-first century. In natural philosophy, later called natural science, Aristotle established methods for investigation and reasoning and provided a theory on how embryos generate and develop. He originated the theory that an organism develops gradually from undifferentiated material, later called epigenesis.

David Starr Jordan studied fish and promoted eugenics in the US during the late nineteenth and early twentieth centuries. In his work, he embraced Charles Darwin s theory of evolution and described the importance of embryology in tracing phylogenic relationships. In 1891, he became the president of Stanford University in Stanford, California. Jordan condemned war and promoted conservationist causes for the California wilderness, and he advocated for the eugenic sterilization of thousands of Americans. Like many American eugenicists of the early twentieth century, Jordan combined ideas of Mendelian genetics and of Darwinian natural selection to form a basis for limiting or encouraging reproduction in certain individuals and groups based on their perceived hereditary fitness. Like other eugenicists, Jordan s attempt to control the reproductive fate of entire populations marked an episode in the history of reproduction and biology in which its concepts increasingly influenced the social and cultural contexts.