200 THE SCENT OF FLOWERS AS A MEANS OF ATTRACTING ANIMALS. 



posing animal excreta. The West Indian Aristolochia Gigas has the scent of old 

 decaying tobacco, and the red-brown flowers of Calycanthus smell like fermenting 

 wine, quite unlike the woody branches, which have a pleasant odour reminding one 

 of cloves. It has already been stated that flowers provided with indoloid scents 

 resemble animal corpses in their colouring, having usually livid spots, violet streaks, 

 and red -brown veins on a greenish or fawn-coloured background. 



The aviinoid scents come next to the indoloid. Under this name are comprised 

 all those volatile substances which diffuse into the air and have an amine as their 

 foundation, either a primary, secondary, or tertiary amine, according as to whether 

 one, two, or all three of the hj^drogen atoms of the ammonia are replaced by an 

 alcohol radical. It has been shown that the curious odour of the Hawthorn 

 (Cralcegus) is due to trimethylamine. It is very probable that in numerous other 

 flowers with similar scent trimethylamine or a related compound — ammonia — is 

 developed. The smell of Hawthorn flowers is repeated with slight modifications in 

 the flower of the Pear (Pyrus), the Medlar {Mespilus), the Mountain Ash (Sorhus), 

 the shrubby Spiraeas {Spircea ulmifolia, chamcBdry folia, &c.), the Dogwood 

 {Cornus sanguinea), the Wayfaring Tree and Guelder-rose {Vibumuni Lantana, 

 Opidiis), the Chestnut (Castanea), the Elder (Sambucus raceviosa), the Traveller's 

 Joy (Clematis Vitalba), and the Barberry {Berberis). The scent which is liberated 

 from the flowers of the Tree of Heaven (Ailanthus), of the Horse-chestnut {jEtiCtdus 

 Hippocastanum), of the Flowering Ash {Fraxinus Ornus), and of the Evening 

 Primrose {(Enothera), resembles that of GratcBgus more remotely. The flowers of 

 the Ivy (Hedera) develop a scent which reminds one of herring-pickle, those of the 

 Alpine Poppy (Papaver alpinum), partly of Hawthorn, partly of Musk. Two 

 North American plants, viz. Pachysandra and Sanguinaria, produce a scent 

 distantly resembling ammonia which proceeds, apparently, from an amine com- 

 pound. Under this division, finally, should be placed that odour so repulsive to the 

 human olfactory organ which is produced by the flowers of the already-mentioned 

 Melianthus (see p. 171). 



The third group, that of the bemoloid scents, is composed of such as are formed 

 from the so-called aromatic bodies. They are compounds with a benzole nucleus 

 in which the various hydrogens of the benzole are replaced by alcohol and acid 

 radicals. The Eugenol (or oil of cloves) in the flowers of many Pinks {Dlanthus 

 Caryophyllus, plumarius, superbus), the Cinnamyl- alcohol which smells like 

 Hyacinths, the Salicylic aldehyde in the flowers of the Meadow-sweet {Spircm 

 Ulmaria), the Counuirin in the flowers of the Woodruff" (Asperula odorata), the 

 Vanilla-like scent in the flowers of the Heliotrope {Heliotr opium) are all well- 

 known chemical compounds. I would also include with these the scents of the 

 Lilac (Syringa vulgaris), Lily of the Valley (Convallaria majalis), Mignonette 

 (Reseda odorata), Jessamine (JasminuTn officinale), Auricula (Priviula Auricnhi), 

 Honeysuckle (Lonicera Cap)vifolium), Acacia (Robinia Pseudacacia), Violet (Viola 

 odorata), Cyclamen (Cyclamen Furopceum,), Paulo wnia (Paulownia imperialis), 

 and of Ilang-Ilang (Cananga odorata). 



