313 GENERAL VIEW OF THE BOTANY OF SWAN RIVER. 



character of the Australian forests, namely, in their leaves, 

 or the parts performing the functions of leaves, being ver- 

 tical, or presenting their margin, and not either surface, to- 

 wards the stem : both surfaces having consequently the 

 same relation to light. 



" This economy, which uniformly takes place in the 

 Acacice, is in them the consequence of the vertical dilatation 

 of the foliaceous footstalk; while in Eucalyptus, where, 

 though very general, it is by no means universal, it proceeds 

 from the twisting of the footstalk of the leaf." 



To this quotation it may be added that these two genera 

 still more uniformly agree in the similarity of the opposite 

 surfaces of their leaves. But this similarity is the indi- 

 cation of a more important fact — namely, the existence 

 equally on both surfaces of the leaf, of those organs, for 

 which, as I believe them to be in general imperforated, I 

 have adopted the name of cutaneous glands, but which by 

 most authors are denominated pores, or stomata of the 

 epidermis. 



In leaves, especially of trees and shrubs, these glands are 

 generally found on the under surface only ; while among 

 arborescent plants in a very few instances, as in several 

 Conifer ce, they are confined to the upper surface. 

 31] In addition to the two extensive New Holland tribes 

 here mentioned, there are many other cases in which these 

 organs occupy both paginse ; and I am inclined to think 

 such cases more frequently occur on that continent than in 

 any other part of the world. It is at least certain that on 

 this microscopic character, of the equal existence of cuta- 

 neous glands on both surfaces of the leaf, depends that 

 want of lustre which is so remarkable in the forests of New 

 Holland. 



