184 BOTANY. [CHAP. v. 



in common, and at the same time not possessed by the 

 members of any other group. From the philosophical 

 point of view, supported by evidence of the mutation 

 and change in species that cannot be denied by the 

 bitterest opponents of evolution, it may be assumed 

 that the primary divisions of the vegetable kingdom 

 enumerated above originated as side branches from pre- 

 viously existing groups. From Cryptogams as the 

 starting-point of plant life we get, as already shown, 

 Phanerogams; the latter appearing as Gymnosperms, 

 that were followed later in time by Angiosperms ; the 

 latter again being first evolved as Monocotyledons, fol- 

 lowed by Dicotyledons. 



It is important to understand that in the gradual 

 evolution of plants, the groups do not follow each other 

 in an unbroken sequence, by which is meant, the struc- 

 tural peculiarities characterizing a given group are not 

 evolved or supplemental to the characters possessed by 

 the most highly organized members of the group from 

 which it evolved, but in reality new groups originate 

 from the simpler and primitive members of the pre- 

 ceding or parent group, so that the early members of a 

 new group are for a time much simpler in organization 

 than the most perfect forms of the older ; but the new 

 group commences with what may be expressed as the 

 germ of a new idea, and if this new idea better enables 

 its members to hold their own in the struggle for exis- 

 tence, we find the new group gradually surpassing the 

 parent group in numbers and also in distribution in 

 space, due to the advantages derived from the posses- 

 sion of the new feature, which need not necessarily imply 

 increased complexity of structure, but, on the other 



