THE MORPHOLOGICAL COMPOSITION OF PLANTS. 79 



level, appears to have taken place a repetition of the process 

 already observed on lower levels. The formation of those 

 small groups of physiological units which compose the lowest 

 protophytes, is itself a process of integration; and the con- 

 solidation of such groups into definitely-circumscribed and 

 coherent cells or morphological units, is a completing of the 

 process. In those coalescences by which many such cells 

 are joined into threads, and discs, and solid or flattened- 

 out masses, we see these morphological units aggregating 

 into units of a compound kind: the different phases of the 

 transition being exemplified by groups of various sizes, 

 various degrees of cohesion, and various degrees of definite- 

 ness. And now we find evidences of a like process on a 

 larger scale: the compound groups are again compounded. 

 Moreover, as before, there are not wanting types of organi- 

 zation by which the stages of this higher integration are 

 shadowed forth. From fronds that occasionally produce 

 other fronds from their surfaces, we pass to those that 

 habitually produce them; from those that do so in an in- 

 definite manner, to those that do so in a definite manner; 

 and from those that do so singly, to those that do so doubly 

 and triply through successive generations of fronds. Even 

 within the limits of a sub-class, we find gradations between 

 fronds irregularly proliferous, and groups of such fronds 

 united into a regular series. 



Nor does the process end here. The flowering plant is 

 rarely uniaxial it is nearly always multiaxial. From its 

 primary shoot there grow out secondary shoots of like kind. 

 Though occasionally among Phsenogams, and frequently 

 among the higher Cryptogams, 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 

 Phffinogams 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- 



