ODOURS OF FLOWERS 93 



(k) Violet-odour : Viola mirabilis ; Matthiola annua, incana, varia ; Cheiranthus 

 Cheiri, Hesperis matronalis, Leucojum vernum, Gentiana ciliata, Daphne Laureola, 

 Nymphaea coerulea, Sarracenia purpurea; 



(/) Cyclamen-odour: Pyrola uniflora ; 



{m) P aulownia-odour : Glycine chinensis ; 



() Ylang-ylang-odour : Zaluzianskia lychnidea. 



The above-named flowers with odours agreeable to man all conceal their honey 

 much more deeply than the flowers of the former group, so that it is only accessible 

 to insects possessing a moderately long or very long proboscis. Accordingly, the 

 benzoloid odours are agreeable to those insects (bees, moths, and butterflies) which 

 are the most industrious floral visitors. 



4. Paraffin Odours. Among these Kerner includes odours that are peculiar 

 to those acids and alcohols among hydrocarbons described as paraffins. Special 

 forms of them are the valerian odour of Valeriana officinalis, montana, and saxatilis 

 (due to valerianic acid); the rose-odour (due to pelargonic acid), especially character- 

 istic of Rosa centifolia ; the rue-odour of Ruta graveolens (due to oil of rue); the vine- 

 flower-odour (due to aenanthic acid) of Vitis vinifera, Gleditschia triacanthos, and 

 G. sinensis; the linden-odour of Tilia alba, parvifolia, and others; and Aesculus 

 macrostachya ; the nightshade-odour of Datura Stramonium, and others; Mandragora, 

 Petunia, and Paeonia ; the elder-odour of Sambucus nigra and Orchis pallens ; and 

 the goat-odour (due to caproic acid) of Himantoglossum hircinum and Orchis pallens. 



Kerner's ' paraffinoid ' odours seem to me to constitute the least consistent 

 group. The disagreeable odour of rue, of Datura, and of valerian is in such 

 sharp contrast to the delightful fragrance of the vine and rose that I cannot regard 

 the paraffinoid odours as a natural group, in spite of their chemical affinity. More- 

 over, the circle of visitors of the flowers concerned is heterogeneous, including flies 

 and bees, insects which respectively possess the shortest and the longest proboscides 

 and are the idlest and busiest guests. 



Kerner is doubtful whether the odour of honey should be classified here, for it is 

 not due, as formerly supposed, to myricil alcohol (a paraffin derivative). The odour 

 of honey is the commonest of all the odours of flowers. It occurs, according to 

 Kerner, in many natural orders, e.g. in the flowers of the sloe (Prunus spinosa), 

 apricot (P. Armeniaca), cherry (P. avium), almond (Amygdalus communis), Hermi- 

 nium monorchis, Prunus Padus (combined with an aminoid odour, according to my 

 experience), Galium cruciata, vernum, verum (combined with odour of woodruff", in 

 my opinion), Myosotis alpestris. Phlox paniculata, Asclepias, Cynanchum, Corydalis 

 cava, Euphorbia Cyparissias, Salix Caprea, daphnoides, and others ; Cirsium arvense, 

 Angelica officinalis, Heracleum Sphondylium, Meum Mutellina, Pimpinella magna, 

 Alyssum montanum, Erysimum odoratum, Tulipa sylvestris. Allium sibiricum, 

 Chamaemoly, and others ; Polygonum Fagopyrum, Trifolium pratense, resupinatum, 

 Lathyrus odoratus, and others, 



5. Turpenoid Odours. These are such odours as are derived from terpenes, 

 i.e. ethereal oils which do not contain oxygen. These are sometimes enclosed in 

 special cells within the plant-body, sometimes in stalked epidermal glands on the 

 stem or leaves, more rarely on the flowers. Oil of neroli, for instance, produces 



