Summary

Sacks returns to Charles Darwin in this essay to discuss his study of earthworms. The worm's ability to sense external factors such as light and vibrations, combined with the worm's ability to modify its behavior according to circumstance led Darwin to conclude that the earthworm has "the presence of a mind of some kind" (62). Sacks expands Darwin's work on worms to the work of George John Romanes, and others, on jellyfish, which studied the presence of nerves and a nervous system which showed that "jellyfish employed both autonomous, local mechanisms [...] and centrally coordinated activities through the circular 'brain'" (64). This work countered the contemporary 19th century belief that the nervous systems of invertebrates are "radically different from those of vertebrate ones" and rejected the idea of jellyfish and similar creatures as passive beings. Though the nervous system of...