24 HEDWIG ON THE ORGANS OF 



of it, and vice versa. These observations M, 

 Decandolle has made with Ranunculus aquaticus, 

 and other water plants. Mentha viridis, cultii 

 vated in a garden, has about 1800 pores on the 

 under surface of one fmgle leaf; but a stalk of 

 this plant, immersed in water, and left there for 

 some time, will produce new shoots and leaves 

 without pores. The blanched plants (plantes 

 etiolees) are also without them. M. Decandolle 

 has counted about 250 pores upon each surface of 

 the seminal leaves of Sinapis alba and Lepidium 

 sativum, cultivated in the open air; while those of 

 several plants of the same species, raised in the 

 dark, did not show a single pore. In a cellar 

 lighted by six lamps he raised some plants from 

 the seeds of the two species last mentioned, but 

 could not discover more than 150 upon each sur- 

 face of the seminal leaves. 



Some naturalists have .been of opinion that these 

 organs or pores served to elaborate the glaucous 

 dust which covers the leaves of certain plants ; 

 but no such pores are observed on the fleshy 

 fruits, as plums, which, however, are furnished 



