ionone, vanillin).

IV. The ambrosiacal odors (ambergris and musk).

V. The alliaceous odors, with the cacodylic group (asafoetida,
ichthyol, etc.).

VI. Empyreumatic odors.

VII. Valerianaceous odors (Linnæus's _Odores hircini_, the capryl
group, largely composed of sexual odors).

VIII. Narcotic odors (Linnæus's _Odores tetri_).

IX. Stenches.

A valuable and interesting memoir, "Revue Générale sur les
Sensations Olfactives," by J. Passy, the chief French authority
on this subject, will be found in the second volume of _L'Année
Psychologique_, 1895. In the fifth issue of the same year-book
(for 1898) Zwaardemaker presents a full summary of his work and
views, "Les Sensations Olfactives, leurs Combinaisons et leurs
Compensations." A convenient, but less authoritative, summary of
the facts of normal and pathological olfaction will be found in a
little volume of the "Actualités Médicales" series by Dr. Collet,
_L'Odorat et ses Troubles_, 1904. In a little book entitled
_Wegweiser zu einer Psychologie des Geruches_ (1894) Giessler has
sought to outline a psychology of smell, but his sketch can only
be regarded as tentative and provisional.