270 HARMONIES OF VEGETATION. 



daring the night undergoing a gradual change till it acquires iU 

 morning aspect. 



17 One more point worthy of observation, with 

 respect to the harmony of the flower with the sun, is 

 that their time of duration is regulated by the quantity 

 of heat they are intended to collect. 



While some flowers require weeks to fulfil their vegetable economy, 

 there are others which flower so rapidly, (as the common thorn) 

 that there is scarcely time to observe its expansion. St. Pierre 

 mentions, that in the garden of plants at Paris, there is a species of 

 serpentine aloe, without thorns, whose larce and beautiful flower 

 emits a strong smell of vanilla, at the time of its expansion, which is 

 extremely short. It blows only about the month of July, at five in 

 the evening ; yon then see it gradually open its petals, expand itself, 

 and die. By ten at night it is totally faded. 



18. Such then, are the important relations of the 

 corolla to the sun and heat; besides which, it undoubt- 

 edly has numerous other harmonies with the wind, 

 foreign objects, and so on. 



It is very easy to su ppose the carolla is in many instances, intended 

 for other purposes than the regulation of heat. Why has nature 

 given to several plants pending bell-shaped corollas, as with fox- 

 glove, lily of the volley, and others, but to defend the interior parts 

 from rain, wind, &c. Some are provided externally with hair to 

 shelter them from the cold. Otlieis are formed to blow on the 

 surface of the water; such are the yellow roses of the nymphae, 

 which float on the lakes, and consign themselves to the different 

 motions of the waves, without being welted by them, by means of 

 the long and flexible stems to which they are attached. There are 

 other flowers adapted to the wind and to the rain, as those of pease, 

 vhich have little boats that shelter the stamens and pistils. They 

 have, besides, large flags, and are fixed on stalks curved and elastic 

 s a nerve ; so that when the wind blows on a field of pease, yon 



