7-5 MOIIPHOLOGICAL DEVELOPMENT. 



among the higher Crj^togams, the germs of new axes detach 

 themselves under the form of bulbils, and develop separately 

 instead of in connexion with the parent axis ; yet in most 

 Phaenogams, the germ of each new axis maintains its con- 

 nexion with the parent axis : whence results a group of axes 

 — an aggregate of the fourth order. Every tree, by the pro- 

 duction of branch out of branch, shows us this integration 

 repeated over and over again : forming an aggregate having 

 a degree of composition too complex to be any longer deflnftd. 



