294 VEGETABLE ORGANOGRAPHY. 



"What is remarkable in bulbs compared with buds is, 

 that their coats remain for many years : so that a bulb 

 is not only formed of the buds of the year, but of the 

 sheathing coats of preceding years, which are then ex- 

 hausted of all nourishment, but remain under the form 

 of membranes, and thus serve to protect the young offsets 

 either from cold, because they contain several strata of 

 air between their coats, or from wet, because their epi- 

 dermis is silicious and scarcely affected by moisture. 

 There are some bulbs which, like the buds of trees, pre- 

 sent a cottony layer between or outside their coats, as 

 in the Tulip. 



It results from all that I have set forth in this chap- 

 ter, 1st, that buds are the integuments of the young 

 shoots formed by the external foliaceous organs, some- 

 times in their natural state, as the stipules of Ficus and 

 Magnolia, but most frequently converted into scales by a 

 kind of degeneration or semi-abortion caused by their 

 position ; 2d, that the buds of trees, exposed to the air, 

 and those which spring on a level with the surface, or 

 the turiones of perennial plants, and subterranean buds, 

 or the bulbs of the Liliacese, &c. only differ from one 

 another in what must necessarily result from their 

 position, and the stems which bear them. 



