Rise of the Study of Olfaction--Cloquet--Zwaardemaker--The Theory of
Smell--The Classification of Odors--The Special Characteristics of
Olfactory Sensation in Man--Smell as the Sense of Imagination--Odors as
Nervous Stimulants--Vasomotor and Muscular Effects--Odorous Substances as
Drugs.


During the eighteenth century a great impetus was given to the
physiological and psychological study of the senses by the philosophical
doctrines of Locke and the English school generally which then prevailed
in Europe. These thinkers had emphasized the immense importance of the
information derived through the senses in building up the intellect, so
that the study of all the sensory channels assumed a significance which it
had never possessed before. The olfactory sense fully shared in the
impetus thus given to sensory investigation. At the beginning of the
nineteenth century a distinguished French physician, Hippolyte Cloquet, a
disciple of Cabanis, devoted himself more especially to this subject.
After publishing in 1815 a preliminary work, he issued in 1821 his
_Osphrésiologie, ou Traité des odeurs, du sens et des organes de
l'Olfaction_, a complete monograph on the anatomy, physiology, psychology,
and pathology of the olfactory organ and its functions, and a work that
may still be consulted with profit, if indeed it can even yet be said to
be at every point superseded. After Cloquet's time the study of the sense
of smell seems to have fallen into some degree of discredit. For more than
half a century no important progress was made in this field. Serious
investigators seemed to have become shy of the primitive senses generally,
and the subject of smell was mainly left to those interested in "curious"
subjects. Many interesting observations were, however, incidentally made;
thus Laycock, who was a pioneer in so many by-paths of psychology and