STRUCTURE OP PLANTS. 



327 



canals. Experiments with leaves bring out parallel facts ; 

 and this, then, is confirmed, that in ordinary stems the 

 staining of the wood by an. ascending coloured liquid is 

 due, not to the passage of the coloured liquid up the sub- 



Fig. 172. Termination of Vascular System (after Spencer). 



1. Absorbent organ from the leaf of Euphorbia neriifolia. The cluster of 

 fibrous cells forming one of the terminations of the vascular system is here 

 embedded in a solid parenchyma. 



2. A structure of analogous kind from the leaf of Ficus elastica. Here the 

 expanded terminations of the vessels are embedded in the network paren- 

 chyma, the cells of which unite to form envelopes for them. 



3. End view of an absorbent organ from the root of a turnip. It is taken 

 from the outermost layer of vessels. Its funnel-shaped interior is drawn as it 

 presents itself when looked at from the outside of this layer, its narrow end 

 being directed towards the centre of the turnip. 



4. Shows on a larger scale one of these absorbents from the leaf of Panax 

 Lessonii. In this figure is clearly seen the way in which the cells of the net- 

 work parenchyma unite into a closely-fitting case for the spiral cells. 



5. A less-developed absorbent, showing its approximate connexion with a 

 duct. In their simplest forms, these structures consist of only two fenestratod 

 cells, with their ends bent round so as to meet. Such types occur in the cen- 



