96 PECULIAR JUICES. 



Let us now proceed to the excretory secretions : they 

 are of much less importance than the preceding, and 

 consists chiefly of vapors and gases exhaled from flowers. 

 Among these we distinguish the vapor of the Fraxinella, 

 which is elaborated by glands sufficiently large to be vi- 

 sible, and is very combustible. 



Emily. I recollect having seen it burn, by approach- 

 ing a taper to it ; but is not this vapor similar to the ex- 

 halations of the odor of plants ? 



Mrs. B. No ; the odors of plants are undoubtedly an 

 excretory secretion, but are not generally of a combusti 

 ble nature. They are of various descriptions, but it is 

 difficult to determine in what manner to class them, as 

 they affect the olfactory nerves of different people in so 

 different a manner : they have been attempted to be dis- 

 tinguished by the name of aromatic, stimulating, pene- 

 trating, sweet. Flowers, with some few exceptions, 

 (such, for instance, as the rose and the violet,) exhale 

 their perfume only as long as the plant is living ; that 

 which proceeds from the bark, or other parts of the plant, 

 continues to be emitted after death. 



Flowers having an ambrosial smell, exhale it only in 

 the evening, after sunset ; those which have the odor of 

 musk are always of a yellowish purple color, and of a 

 dull appearance, corresponding, it is said, with the dele- 

 terious nature of their perfume. 



The smell of flowers, in general, is considered to be 

 more insalubrious to a person sleeping than awake. 

 Whether it be, that, in the latter case, the animal frame 

 has a more energetic power of resistance to deleterious 

 effects, or from some other cause, is not ascertained. 



Emily. May not this difference arise from plants giv- 

 ing out oxygen during the day, and absorbing it during 

 the night ? 



Mrs. S. No ; the spasmodic effect produced on 

 the nervous system by the perfume of flowers is quite 



531. Of what do the excretory secretions consist'? 532 By wl 

 name have the odors of plants been distinguished! 533. What 

 said of flowers as to exhaling perfume before and subsequent to their 

 death 1 534. What is said of flowers having an ambrosial smell, and 

 of those which have an odor of musk? 535. What is said of the 

 smell of flowers to persons asleep 1 ? 





