Fundulus embryos have had a long history in comparative and embryological research, which also influenced Trinkaus’s choice. For instance, Thomas H. Morgan and Jacques Loeb were both intrigued by the observational and experimental possibilities presented by the clarity of the organism’s eggs and embryos. In 1893, Morgan wrote: “The egg readily lends itself to experiments of all kinds. It is easily kept and has a great amount of vitality and these qualities taken in connection with its large size make it most favourable for experimental studies” (Atz 1986, 112). Morgan went on to conduct experiments on Fundulus to study the effects of interventions on blastomeres in 1893 and 1895, and later, in 1900, on the regeneration of Fundulus tails. For his part, Loeb conducted experiments on Fundulus’s circulatory system and pigmentation patterns. Moreover, the developing eggs of Fundulus were used in the MBL’s embryology course from its very beginning in 1893 until the early 1970s, when the focus of the course shifted towards molecular approaches in developmental biology.