Xll INTRODUCTION. 



which they were acquainted, adhered to the ancient plan of making 

 their classification coincide with natural affinities. Among them 

 the most distinguished were Ceesalpinus, an Italian, who published 

 in 1583, our countryman John Ray, and the more celebrated Tourne- 

 fort, who wrote in the end of the seventeenth century. At this 

 time the materials of Botany had increased so much, that the 

 introduction of more precision into arrangement became daily an 

 object of greater importance; and this led to the contrivance of a plan 

 which should be to Botany what the alphabet is to language, a key 

 bv which what is really known of the science might be readily 

 ascertained. With this in view, Rivinus invented, in 1690, a system 

 depending upon the conformation of the corolla; Kamel, in 1693, 

 upon the fruit alone; Magnol, in 1720, on the calyx and corolla; 

 and finally, Linnaeus, in 1731, on variations in the sexual organs. 

 The method of the last author has enjoyed a degree of celebrity 

 which has rarely fallen to the lot of human contrivances, chiefly on 

 account of its clearness and simplicity ; and in its day it undoubtedly 

 effected its full proportion of good. Its author, however, probably 

 intended it as a mere substitute for the Natural System, for which 

 he found the world in his day unprepared, to be relinquished as soon 

 as the principles of the latter could be settled, as seems obvious 

 from his writings, in which he calls the Natural System primum et 

 nltimum in botanicis desideratum. He could scarcely have expected 

 that his artificial method should exist when the science had made 

 sufficient progress to enable botanists to revert to the principles of 

 natural arrangement, the temporary abandonment of which had been 

 solely caused by the difficulty of defining its groups. This difficulty 

 no longer exists ; means of defining natural assemblages, as certain 

 as those employed for limiting artificial divisions, have been dis- 

 covered by modern botanists ; and the time has arrived when the 

 ingenious expedients of Linnaeus, which could only be justified by 

 the state of Botany when he first entered upon his career, must be 

 finally relinquished. We now know something of the phenomena of 

 vegetable life ; by modern improvements in optics, our microscopes 

 are capable of revealing to us the structure of the minutest organs, 

 and the nature of their combination; repeated observations have 

 explained the laws under which the external forms of plants are 

 modified; and it is upon these considerations that the Natural System 

 depends. What, then, should now hinder us from using the powers 

 we possess, and bringing the science to that state in which only it 

 can really be useful or interesting to mankind ? 



Its uncertainty and difficulty deter us, say those who, acknow- 

 ledgnig the manifest advantages of the Natural System, nevertheless 

 continue to make use of the artificial method of Linnaeus. I do not 



