44 



LEAP-BUDS AND B0LBS. 



wood on which they may be placed. Under ordinary circum- 

 stances, leaf-buds wiU not form anywhere except at the axils * 

 of leaves ; but occasionally they appear from other parts, such 

 as the root (see page 31), the spaces of the stem which lie 

 between the leaves (the internodes), and even from the leaves 

 themselves (see page 33). In all such cases, they are termed 

 adventitious, because of the uncertainty of their appearance. 

 A very remarkable state of them is the embryo-btid, a name 

 applied to the knaurs, knurs, nodules, or hard concretions, 

 found in the bark of various trees, which seem to have, occa- 

 sionally, the power of propagating the individual, notwith- 

 standing their deformed and indurated state. 



The connection between the formation of timber and the action of 

 buds will be considered hereafter, when speaking of the wood-forming 

 power of leaves, which are organs resulting wholly from the develop- 

 ment of buds. 



Bulbs are buds of a particular kind, larger than common, 

 containing an unusual quantity of organizable matter, and 

 separable, spontaneously, from the part which bears them. 



Pig. X.— A. Bulb of Tigor Lily oonti-asted with b. a Leaf-bud. 



They are magazines in which certain plants store up the 

 nutritive matter assimilated by the leaves. The identity of a 

 bulb and a bud, in all essential circumstances, is obvious if the 



* The axil is the acute angle formed by a leaf and stem, at the origin of the f 

 all bodies growing within that angle are said to be axillary. ormei , 



