BUDS. 39 



the summit of its stem. The buttons, as o-ardenors torni tlioin, 

 are of this character. Some species of the Hly bear tliem in tlie 

 axils of the leaves, and they separate from the stem and fall to 

 the earth, and become plants bearing bulbs in their turn. Bulbs 

 are sometimes distinguished into scaly, being covered with scales, 

 as in the lily ; and tunicated, being formed of concentric coats, as 

 in the onion. 



69t At the extremities and sides of tlie fibers of roots, small 

 bodies are observed composed of lax cellular tissue, called spon- 

 gioles, from their resemblance to sponge. It is through the 

 spongioles that all the nourishment of the plant enters, that 

 enters by the root. Duhamel, a long time since, observed that 

 trees exhaust the soil at the extremities of the roots only, but 

 it was reserved for Sennebier to demonstrate, by a very simple 

 experiment, that the spongioles alone absorb fluids from the 

 earth. This he did by talking two carrots of equal size, and 

 immersing the whole of one in water, and the extremities of 

 the roots of another. He found that they both absorbed an 

 equal quantity; but by immersing the whole body of a third, 

 keeping only the spongioles out of the water, none of the fluid 

 was absorbed. When the spongiole is destitute of fluid, it con- 

 tracts, and lies close to the fiber to which it is attached, and 

 hence is not easily discovered in pulling up a root ; but by im- 

 mersing the fiber in a tumbler of water, the spojigioles be- 

 come turgid, and are easily observed. 



Section 5. — Buds. 



70. In the axil of the leaf of a dicotyledonous tree or shrub, 

 we may observe in the early part of the summer a small protu- 

 berance, which will continue to increase until autumn ; when it 

 will have assumed the form of a conical body composed appa- 

 rently of scales. This is the bud, which is destined in the fol- 

 lowing year to produce a branch, or flowers and fruit. These 

 small bodies found in the axils of leaves, are vital points, in 

 which seems to be deposited the vital power during the season 

 of repose, and from which development commences as the sea- 

 son of vegetation returns. That they are important organs, and 

 demand our strictest observation, is apparent from the fact 

 of their being, in many instances in the vegetable economy, the 

 seat of vitality ; and it is from this circumstance that we are 



Wliat are button onions ? How are bulbs sometimes distinpuisliecl ? — 

 69. \Vluitare spongioles ? Give the experiment of Sennebier. — 70. Wher© 

 *re buds formed } What are they ? 



