THE MORPHOLOGICAL COMPOSITION OF PLANTS. 75 



of cells bound up into a continuous whole, must be regarded 

 as an aggregate of the third order. The inference drawn 

 from analysis, and verified by a synthesis that corresponds in 

 a remarkable manner with the facts, is, that those compound 

 parts Avhich, in Endogens and Exogens, are called axes, 

 have really arisen by integration of such simple parts as in 

 lower plants are called fronds. Here, on a higher level, ap- 

 pears to have taken place a repetition of the process already 

 observed on lower levels. The formation of those small 

 groups of physiological miits which compose the lowest 

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

 solidation of such groups into definitely-circumscribed and 

 coherent cells, is a completiag of the process. In those 

 coalescences, variously carried on, by which many such cells 

 are joined into threads, and discs, and soHd 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. Once more do we now find evidences of a like process 

 on a larger scale : the compound groups are again com- 

 pounded. And, as before, there are not wanting types of 

 organization 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 limitsof 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 



