OF BUDS. 287 



from being underground are etiolated and fleshy, and 

 come under the class of foliaceous buds ; whilst the radical 

 buds, produced by the dilated petioles of Hemerocallis, 

 are examples of petiolaceous ones. We know that in 

 this class we can find none of those which suppose the 

 existence of stipules. 



Although aerial and subterranean buds have the same 

 origin, the difference of their position produces diver- 

 sities in their nature, which deserve to be analyzed. 



Aerial buds owe to their position the peculiar texture 

 of their scales, which, exposed to the action of air and 

 light, evaporate much, and are found reduced, as it 

 were, to their fibrous tissue. These characters go 

 on diminishing in the inner scales, which from the 

 same circumstance evaporate less, and retain the juices 

 more. 



The buds have eminently two uses to perform — to 

 defend the young shoots from damp and cold. 



In the first respect the scales are generally so nume- 

 rous and applied to one another so exactly, that the 

 rain cannot penetrate their interstices before their 

 expansion. Several buds present, moreover, a parti- 

 cular protection against moisture, in having their scales 

 covered over with a varnish or viscid layer of a resinous 

 or waxy nature, which is not miscible with water, and 

 thus prevents its introduction. The buds of the Horse- 

 chestnut present this in a high degree ; those of the 

 Alder and Black Poplar are also invested with a 

 resinous matter, which defends the young shoots from 

 moisture. 



With regard to temperature, the superposition of the 

 scales is a means cf protection from cold, because each 

 of them incloses a certain quantity of air ; moreover, 

 several buds are invested externally with a close down, 

 and some have the inner cavity full of a soft thick down 



