LECT. IX.] HYBEKNACULA GEMS. 4.77 



of the atmosphere has arrived at that point which 

 the excitability of the gem demands for arousing 

 its vital energy into activity, the outer scales 

 being no longer useful, drop off; but the inner 

 ones remain and assume the functions of leaves, 

 until the real leaves are fully expanded. All the 

 gems on a tree, however, do not open at the same 

 time, for the current of fluid in the sap vessels 

 communicating with the terminal gems being more 

 direct than that which supplies the lateral gems, 

 the former always open sooner than the latter. 

 Flower gems almost always open before leaf gems 

 on the same tree; but flower gems which are 

 at a distance from leaf gems, generally fall with- 

 out producing fruit ; and perhaps they possess al- 

 together less individuality than leaf gems, yet 

 flower gems live and flourish when they are de- 

 tached and then budded near a leaf gem on the 

 same or on another stock. We are now treating, 

 however, of the conservative organs only of plants ; 

 I shall, therefore, at present, not enter upon the 

 examination of the flower gem; but pass on to 

 treat the contents of the leaf gem ; or leaves and 

 their appendages. 



LEAVES are organs of essential importance to 

 the vegetable. They are, also, objects of great de- 

 light and interest, whether we examine them indi- 

 vidually as the clothing of a single plant, or col- 

 lectively as producing the lively freshness of the 



