lii FLORA ODORATA— HISTORICAL SKETCH 



being either inodorous or having an unpleasant smell. White 

 flowers are the most numerous; 1124 species out of 4200 are 

 white, and 187 of these have a scent; 931 (77 perfumed) are 

 yellow, next in order comes red with 823, of which 84 give 

 forth a perfume ; then blue 594 (34 scented), and violet 308, 

 only 13 of which have any perfume. The remaining 400 

 kinds are of various shades of colour, and only 28 of them 

 have a pleasant smell.' 



Another authority has been making researches into the 

 origin of perfume in flowers, and comes to the conclusion 

 that (1) the essential oil is generally found localised in the 

 epidermic cells of the upper surface of the petals or sepals. 

 It may exist upon both surfaces, especially if the floral parts 

 are completely concealed in the bud. The lower surface 

 generally contains tannin or pigments derived therefrom. 

 (2) The chlorophyll seems in all cases to give rise to the 

 essential oil. (3) The disengagement of the perfume of 

 the flower makes itself perceptible only when the essential 

 oil is sufficiently disengaged from the intermediate pro- 

 ducts that have given rise to it, and is found, in a manner, 

 in a ratio inverse to the production of tannin and pigments in 

 the flower. This will explain why flowers with green petals 

 have no odour ; why white or rose-coloured flowers are most 

 often odoriferous; why many of the Compositce, which are 

 rich in tannin, have the disagreeable odour that they are 

 known to possess ; and why the white Lilac and forced Roses 

 take on a finer perfume. 



