SOCIAL AND POLITICAL ECONOMY. 203 



duties formerly performed by leaves shall henceforth 

 be undertaken by some other organ or some other part. 

 The work must be done — what is to do it ? Plants 

 of various orders have found out that the easiest 

 raised substitutes for leaves are phyllodes, which are 

 developed by simply flattening the branches, leaf- 

 stalks, and flower-stalks, providing them with carbon- 

 feeding mouths {stomata), and filling their improvised 

 cells with chlorophyll or " leaf-green," so that the}- 

 can perform all the functions of ordinary leaves, 

 such as decomposing carbonic acid, distilling vapour 

 into dew, and collecting rain. This is the origin of 

 the rigid leaf- like parts of the Butcher's Broom 

 {Ruscus acnlcatns) ; the elegant and grass-like leaves 

 of the Grass Pea {Lathyrns nissolia), which takes its 

 common name from the fact, although the " grass 

 leaves " are not leaves at all, but phyllodes or flat- 

 tened leaf-stalks ; of the Meadow Vetchling {Lathyrns 

 aphacd), whose flattened stipules do duty for true 

 leaves, of which the plant has none except on the 

 first petiole ; and more especially and universally 

 in the Australian Acacias, whose apparent flattened 

 leaves are really phyllodes, or modified leaf- stalks, 

 after the fashion just described. Singularly enough, 

 as any one may prove by experiment, the first real 

 leaves of the Acacia seedling are compound, exactly 

 like the properly constituted leaves of the Acaciae of 

 other countries — showing that the Australian branch 

 of the family, for reasons of its own, has modified 



