324 ODOROGRAPHIA. 



See also series i., p. 26.] — "It is plainly evident that this oil is 

 generated in the same manner as in the preceding case (that of 

 Jasmin). 



"Violet. The oil is here similarly located. It is necessary, 

 however, in this instance, before applying the reagent, to immerse 

 the section for a few minutes in a solution of tungstate of sodium, 

 in order to precipitate the tannin. The essential oil then appears 

 of a bright red colour. 



" Tuhereuse. In this case the essential oil is located on the lower 

 surface of different parts of the perianth. The intermediate cells 

 contain a fixed oil, and the presence of tannin is scarcely traceable. 

 Thus, in consequence of the abundance of chlorophyll in the first 

 place, of the almost complete absence of tannin, also probably by 

 reason of the presence of a fixed oil which has drawn it towards 

 the periphery, the essential oil is carried towards the lower surface. 

 The intense odour of tubereuse only commences to reveal itself 

 when the oil is enabled to form itself into small drops under the 

 influence of the reagent. 



" Orcnir/e blossom. The reagent discloses the presence of several 

 distinct essential oils in the orange blossom. First there is that 

 contained in the secretory glands, which occur on the lower surface 

 of the petals or sepals. This is not pure neroli, as is generally 

 supposed, but an oil analogous to that of petit-grain." — [Mesnard 

 evidently overlooks ihe fact that neroli is not a true odour of 

 orange blossom, such as is obtained by a cold process of extraction,, 

 but a modification thereof, the modification being wrought by the 

 action of heat and contact of the molecules of oil with aqueous 

 vapour — the product being very inferior in fragrance.] — " By 

 skilfully eliminating these glands in an unopened bud, the 

 agreeable odour of the flower when it afterwards expands is in no 

 degree injured. Essential oil is also found in the epidermis of 

 both surfaces of the petals and even upon the periphery of the 

 petaloid filaments of the stamens. By systematically preventing 

 in various ways the liberation of the perfume in these different 

 parts of the flower, I have been able to ascertain that the odour 

 corresponding to the finest neroli is solely produced on the upper 

 surface of the petals, and I have proved that the odour of this 

 flower is a compound one. 



