432 SKETCH OF PALEOBOTANY. 



system-making has been so commonly conducted. Systems of classifi- 

 cation had come to be regarded as the end of science, when they are at 

 best only the means. But it is not to be wondered at that this was so, 

 since it was not uutil quite recently that science could be fairly said to 

 have any end other than to collect facts and build systems. Not until 

 the laws of genetic dependence among the forms of organized life, as 

 taught by Lamarck in 1809 and enforced by Darwin in 1859, had begun 

 to be recognized within the last twenty years, was any such grand re- 

 sult thought possible as that of ever finding out how existing forms 

 have come to be what they are. With the growth of this conception 

 all attempts at classification gradually became revolutionized in their 

 spirit and aim, and from being merely logical and ideal they tended to 

 become practical and real. Whereas formerly some collected facts for 

 the sake of facts, and others built systems for the sake of systems, now 

 all collect facts for the sake of systematizing them and systematize them 

 in order to learn what they teach j for neither without facts nor with- 

 out system can we ever arrive at truth. 



It is customary with botanists to speak of artificial systems of classifi- 

 cation as contrasted with the natural system. It is commonly supposed 

 that the system of Linnaeus was wholly artifical, and the impression 

 equally prevails that that of Jussieu was the true natural one. But in 

 the progress of human discovery no such sudden leap ever takes place. 

 The truth is that all systems have aimed to be natural and that none 

 have wholly succeeded. But there has been progress in the concep- 

 tion of what constitutes a natural system. The most that the older bot- 

 anists aimed to secure was a logical system, and it was supposed that 

 the logical necessarily represented the natural. 



1. TYPES OF VEGETATION. 



The vegetation of the globe has always been divided into certain ob- 

 vious groups which may be called types, the word "type" being here 

 used in a very general and indefinite way. These types of vegetation 

 have various systematic values. The following table contains the prin- 

 cipal ones, with a brief explanation accompanying each : 



Synoptical View of the Types. 



Cryptogams. — Flowerless plants. 



Cellular Cryptogams.— Devoid of vessels or vascular bundles ; e. g., 



sea-weeds, mosses. 

 Vascular Cryptogams.— Raving vascular bundles— fibers, ducts, etc. 

 Filices. — Perns. 



EteocarpecB.— Inconspicuous plants, of interest chiefiy as ap- 

 pearing to form the transition from the Cryptogams to the 

 Phaenogams through the Cycadaceae ; e. g., Marsilia, Sal- 

 vinia, AzoUa. 



