THE FATE OF CANCER: Within a squamous cell carcinoma, tumor cells fluoresce green, indicating that they are derived from basal cells.COURTESY OF CATHY MENDELSOHN
Marine invertebrates may be unassuming creatures, but at the turn of the 20th century they found themselves at the heart of a scientific controversy. In 1891, the German biologist Hans Driesch claimed that each of the four cells in an early-stage sea urchin embryo, if separated, could give rise to an entire larva. Four years earlier, however, Laurent Chabry’s experiments had shown that each cell from an equally early-stage invertebrate—a sea squirt, or tunicate, which has a chordate larva—could only make a partial embryo. To resolve the conflict, Edwin Conklin spent the summer of 1904 hunched over a light microscope in Woods Hole, Massachusetts, observing the development of one of these tunicates, Styela partita. His detailed drawings of the embryos’ bright yellow crescent and four ...
