THE 



PHILOSOPHICAL MAGAZINE 

 AND JOURNAL. 



I. On the Nourishment produced to the Vlant hj its Leaves. 

 By Mrs. Agnes IjiutTsoN. 



To Mr. Tilloch. 



SlJi, — X SHALL now continue the account begun in my last let- 

 ter, tending to prove the different manner which nature pursues 

 in distributing the nourishment the vegetable world requires in 

 four different ways; viz. by a common root, by the agency of a 

 bulb, by the cuticle of leaves, and by a sort of pump inserted 

 into another plant. I have shovrn in evergreens, in firs, and in 

 water plants, that no nourishment whatever is by them taken 

 in by any other vehicle than the root, though some points and 

 hairs may assist them in receiving those various juices that pro- 

 duce the bark mixture, and supply the oil to humectate and lu- 

 bricate the spiral v/ire. 



In trees, shrul)s, herbaceous, annuals, and all those of the kind 

 which prove luxuriant plants, 1 have given examples of those 

 fed by the root and atmosphere ; where the size of the plant, 

 the quantity of their leaves, and the consequent evaporation 

 and exhaustion are svch, that thev must require all the nutriment 

 that can be bestowed hy both. Here the root not onlv does its 

 office thoroughly, l)ut the leaves also, expanded and stimulated 

 by light, are constantly receiving nourishment from the boimteous 

 dews, as well as a varietv of liquids and gases from the hairs and 

 retorts : yet so admirablv is the exterior managed to guard them 

 from the too copious evaporation, that every single leaf is co- 

 vered by many skins, two or three of which being impervious 

 to water, allow air alone to exude. Thus all that passes out 

 from tlie leaves is converted into oxygen for the benefit of man 

 Jtnd animals, and only assumes its watery form when it escapes 

 confinement. This circumstance alone might prove to those 



Vol. 45. No. 201. Jan. 1815. A 2 who 



