364 ELEMENTARY ORGANS. CHAP. l 



not discoverable in the embryo, nor even in the 

 young plant at a very early period, but only when 

 the parts have been fully developed, in which stage 

 they are discoverable in most plants without 

 much difficulty, pervading the ramifications of the 

 branched Lichens, and the stem of the Mosses ; 

 surrounding the fibrous tubes of herbaceous plants, 

 and constituting also longitudinal fibre ; and inter- 

 mingling themselves even with the fibrous tubes of 

 woody plants, and constituting part of the ligneous 

 layers, as well as the prominent ridges with which 

 the surface of vegetables is marked. In the finer 

 and more delicate parts of the plant they are also 

 equally prevalent, accompanying the nerves of the 

 leaves and petals, and forming part even of the 

 stamens and pistils. But in these fine and delicate 

 organs they assume a different aspect, and acquire 

 a degree of consistence resembling that of the eel- 

 Contain- lular tissue. They are generally found to contain 

 iog a juice. a j u i CCj w hj cn i s sometimes clear and limpid, and 

 sometimes thick and coloured, communicating its 

 colour to the tubes. In the Vine this juice is 

 watery ; but in the Fir-tree it is resinous. 



SECTION III. 



Apertures. 



Species. IT has been seen in the foregoing analysis of the 

 elementary or other organs, that the continuity of 



