BOTANICAL CLASSIFICATION. 343 



698. Even the great classes cannot be arranged in a single 

 line, beginning with the highest Phaenogains and leaving the 

 lowest in contiguit}' with the higher Cryptogams. The Dicoty- 

 ledons take precedence of the Monocotyledons in rank. Yet a 

 part of them, the Gymnosperms, are much the lowest of all 

 known Phsenogams as regards simplicity of floral structure ; 

 and through them only is a connection with the higher Cryp- 

 togams to be traced. The Monocotyledons stand upon an iso- 

 lated side line, and have no such simplified representatives. 

 In placing the latter class between the Dicotyledons and the 

 Acrogens, the chain of affinities is widely sundered. If, yield- 

 ing to a recent tendenc}', we raise the Gymnosperms to the 

 rank of a class, and place it between the Monocotyledons and 

 the Acrogens, then the much nearer relationship of Gymno- 

 sperms to Angiosperms through Gnetaceae and Loranthaceae is 

 not respected. (606, &c.) 



699. Nor can the angiospermous Dicotyledons be disposed 

 lineally according to rank. The apetalous and achlamydeous 

 must be the lowest. Some are evidently reduced forms of Poly- 

 petalae or even of Gamopetalae : the greater part cannot without 

 violence be thrust into their ranks. The Gamopetalae, especially 

 those with much floral adnation, should represent the highest 

 type, the organs being at the same time complete and most dif- 

 ferentiated from the foliar state. If a natural series could be 

 formed, these would claim the highest place, with the Compositae 

 perhaps at their head. In the Candollean sequence, they occupy 

 the middle ; and the series begins, not without plausible reason, 

 with orders having generally complete blossoms, and such as 

 most freely and obviously manifest the homology of their organs 

 with leaves, then rises to those of greater and greater combi- 

 nation and complexity, and ends with those plants which, with 

 all their known relatives, are most degraded or simplified by 

 abortions and suppressions of parts which are represented in the 

 complete flower. These are low in structure, equally whether 

 we regard them as reduced forms of higher types, or as forms 

 which have never attained the full development and diversifica- 

 tion which distinguish the nobler orders. 



700. Actual classifications, in their leading features and in 

 their extension to the cohorts, orders, &c., must be studied in 

 the systematic works where they are brought into use. In 

 these are the applications of the principles which are here 

 outlined. A separate volume of this text-book should illustrate 

 the structure, relations, and most important products of the 

 phaenogamous natural orders, as another is to illustrate the 



