490 THE UNIVEESE. 



The secretion of the perfume is usually continuous, be- 

 ginning at the time the flower opens and ceasing when it 

 fades. Even when the corolla, being altogether ephemeral, 

 only lives for a few minutes, it is still observed to perfume 

 the air during these brief moments. This is seen in the 

 magnificent Cactus grandiflora. Quite inodorous a few 

 instants before it blows, it discharges a scented cloud 

 when, towards twilight, its calyx opens; l>ut the enchant- 

 ment vanishes before midnight, with the death and decom- 

 position of the flower. 



Some flowers of nocturnal habits, which do not disdain 

 to lend life to the night, shed their perfumes only ckmng 

 the darkness; these are the bats of the vegetable kingdom. 

 Their sombre mournful hue has often led botanists to saddle 

 them with unpleasing names: tr'isth or nocturnns are their 

 designations for nearly all the plants Avhich present this 

 singularity, as for instance the Pelargonium triste, the 

 Gladiolus tristis, and the Cestrum nocturnum. 



The emanations from plants produce upon us physio- 

 logical effects which are well worth studying. If too con- 

 centrated they ma}^ give rise to serious symptoms, to con- 

 vulsions and spasms, or they may even induce death. 



purpose it was employed in sucli quantities that Fathei- Sanut relates that •')0(i 

 camels were employed to bring it from Damascus. Mahomet II. also, after the 

 taking of Constantinople, ordered St. So]jhia to be washed in the same way. 

 According to Father Catrou's account, the Princess Nourmahal surpassed both, 

 for she collected sufficient rose-water to fill a canal, on which was launched a bark 

 which bore her, accompanied by the Great Mogul. Indeed it was during this re- 

 markable trip that the essence of rose was discovered, having formed at the sur- 

 face of the artificial lake owing to evaporation caused liy the sun. 



The essential oil of roses is one of the most exquisite and dearest perfumes, and 

 justly bears the title of attar or sweetest of fragrances. About 100 lbs. of flowers 

 are requisite to obtain nine to twelve drachms (avoirdupois) of this oil, which 

 comes to us from the East and India, and which is often called butter of roses. 

 Hippocrates and Galen were acquainted with this product, and often employed 

 it in medicine; now-a-days it is only employed to perfume linen and rooms. 



