A memoir of olfaction.

Osphreiology, though beginning with Aristotle, and the title of a classical monograph from 1819 by Cloquet, has, like the human sense of smell itself, played a relatively modest role, compared to other sensory functions. The anatomical and physiological connections of the nose to the brain proved to be more complex than those of sight, hearing and even touch, and were therefore poorly understood before the second half of the 19th century. Moreover, the close association between smell and taste gave rise to much controversy regarding the respective roles of the first and the fifth cranial nerves. Next, came the unfolding of the evolutionary influence of cerebral structure and function--viz Broca's "limbic" concept, and the "olfactory desert" in the brains of "anosmatic" animals, Jackson's "uncinate" seizures featuring olfactory hallucinations brought the hippocampal formation into focus. Finally, there were the clinical manifestations of hyposmia and hyperosmia, from "coryza", the common cold, to injury or neoplasms causing hyposmia, as well as some endocrine alterations causing hyperosmia. (And let us not forget Charles Huysman's "Against the Grain" and Marcel Proust's evocative fragrant madeleine.).