Lily-kin and Rose-kin 129 



The walls of some of these are queerly pitted, 

 and those of others are beautifully marked with 

 raised rings or spirals. 



When the plant is growing actively the largest 

 vessels generally contain but a film of fluid cover- 

 ing their walls, while the rest of the space within 

 them is filled with air. 



The tubes, which are the most important part of 

 the bast, have thin walls with delicate tracery, and 

 are the route by which fluids descend from the 

 leaves toward the roots. 



The water which a growing plant absorbs from 

 the soil holds in solution many mineral and chemi- 

 cal substances. This liquid is " crude sap," and it 

 is the material upon which three magicians work 

 together. The green coloring-matter in the leaves, 

 the sunlight falling upon them, and the carbon 

 dioxide in the air about them, are the efficient trio. 



And the result of their subtle alchemy is 

 " digested sap," which moves downward from the 

 leaves into all the growing parts of the plant, 

 travelling always through the bast. 



When Nature is about to make a new fibre-vas- 

 cular bundle, in lily-kin or in rose-kin, a little of 

 the cellular substance of the growing stem experi- 

 ences a change of character, and becomes set aside, 



