When we are concerned with the fragrances of flowers it would seem that we are far removed from the human sexual field, and that their sexual effects are inexplicable.  It is not so.  The animal and vegetable odors, as, indeed, we have already seen, are very closely connected.  The recorded cases are very numerous in which human persons have exhaled from their skins—­sometimes in a very pronounced degree—­the odors of plants and flowers, of violets, of roses, of pineapple, of vanilla.  On the other hand, there are various plant odors which distinctly recall, not merely the general odor of the human body, but even the specifically sexual odors.  A rare garden weed, the stinking goosefoot, Chenopodium vulvaria, it is well known, possesses a herring brine or putrid fish odor—­due, it appears, to propylamin, which is also found in the flowers of the common white thorn or mayflower (Crataegus oxyacantha) and many others of the Rosaceae—­which recalls the odor of the animal and human sexual regions.[77] The reason is that both plant and animal odors belong chemically to the same group of capryl odors (Linnaeus’s Odores hircini), so called from the goat, the most important group of odors from the sexual point of view.  Caproic and capryl acid are contained not only in the odor of the goat and in human sweat, and in animal products as many cheeses, but also in various plants, such as Herb Robert (Geranium robertianum), and the Stinking St. John’s worts (Hypericum hircinum), as well as the Chenopodium.  Zwaardemaker considers it probable that the odor of the vagina belongs to the same group, as well as the odor of semen (which Haller called odor aphrodisiacus), which last odor is also found, as Cloquet pointed out, in the flowers of the common berberry (Berberis vulgaris) and in the chestnut.  A very remarkable and significant example of the same odor seems to occur in the case of the flowers of the henna plant, the white-flowered Lawsonia (Lawsonia inermis), so widely used in some Mohammedan lands for dyeing the nails and other parts of the body.  “These flowers diffuse the sweetest odor,” wrote Sonnini in Egypt a century ago; “the women delight to wear them, to adorn their houses with them, to carry them to the baths, to hold them in their hands, and to perfume their bosoms with them.  They cannot patiently endure that Christian and Jewish women shall share the privilege with them.  It is very remarkable that the perfume of the henna flowers, when closely inhaled, is almost entirely lost in a very decided spermatic odor.  If the flowers are crushed between the fingers this odor prevails, and is, indeed, the only one perceptible.  It is not surprising that so delicious a flower has furnished Oriental poetry with many charming traits and amorous similes.”  Such a simile Sonnini finds in the Song of Songs, i. 13-14.[78]