Today, the idea that it could be useful to trace cell lineages makes perfect sense, even if the work is difficult and not many researchers are willing to invest the tremendous dedicated energy required. Following a cell lineage in its earliest sense means, tracking a cell in an embryo through each of its cell divisions as far as possible. Edmund B. Wilson's essay resulting from that lecture captures the state of the field in the late 1890s. Each organism, Wilson noted, arises through the processes of a complicated mechanism and also of its past, including its evolutionary history. Sometimes, the individual developmental ontogeny may seem to repeat the ancestral development or phylogeny, as Haeckel had argued. Wilson felt that the relationship was not one of repetition, however, but of reminiscences from past adaptations that are modified by environmental and other conditions. And, yes, cell lineage studies had shown that the reminiscences occur even at the earliest developmental stages.