128 Trans. Acad. Sci. of St. Louis. 



our own flora, up to a point somewhat after the middle of the 

 century, were based on this system, which, when the purpose 

 of the student was to find the name of a plant, has scarcely 

 been equaled by any other ; yet it had one very great defect, 

 in that plants which were obviously related might come to 

 stand far apart in it, so that the suggestion of this relation- 

 ship would be lost on the user of a book in which it was 

 followed. Even before the close of the preceding century, 

 efforts had been turned to the arrangement of a natural se- 

 quence of the higher groups of plants, so that those which 

 possess a number of important and correlated characters in 

 common might be brought together, leaving the tracing of 

 any given species to its place in the system for a quite inde- 

 pendent artificial key, — the Linnean, for instance, or some 

 other specially fancied by the writer or suited to his purposes. 

 To the Jussieus the inception of this movement in a modern 

 sense is due, and the elder DeCandolle stands out prominently 

 among those who amplified and bettered it ; and yet the suc- 

 cess of these earlier seekers for a natural system was but par- 

 tial, and in the summation of their conclusions, as exemplified, 

 for instance, in the great Genera Plantarum of Bentham and 

 Sir Joseph Hooker, though many of the resultant groups, 

 even no higher than orders, possess a very puzzling com- 

 plexity because of the insertion of aberrants, there still re- 

 main many, as, for instance, a large part of those constitut- 

 ing the so-called Apetalae, which are obviously little more 

 than makeshifts, loose-jointed in themselves and with scarce 

 concealed affiliations of the most diverse kinds. As early as 

 the middle of the century, by his comparative developmental 

 studies of the gymnosperms and higher cryptogams, Hof- 

 meister laid the foundations of a more rational system, which, 

 largely through the labors of Alexander Braun and Eichler, 

 culminated in the phylogenetic system of Engler, which marks 

 the close of the century. 



Somewhat comparable needs and advances have marked the 

 knowledge of the cryptogams. The ferns and their allies 

 early differentiated themselves from the remainder of this 

 great second group of Linnaeus, and the mosses and liver- 

 worts as quickly came to be recognized as forming another 



