INTRODUCTION. 



The notion of classing species according to the likeness they bear to 

 each other, which is the foundation of the Natural System, must have 

 originated with the first attempts of man to reduce natural history to a 

 science. When our forefathers spoke of " grass, and herbs yielding seed, 

 and fruit trees yielding fruit, of moving creatures that have life in the 

 water, of fowl that fly above the earth, and cattle and creeping thing," 

 they employed the very same principles of arrangement which are now 

 in use, — rudely sketched, indeed, but not more so than the imperfection 

 of knowledge rendered unavoidable. At that time no means existed of 

 appreciating the value of minute or hidden organs, the functions or even 

 existence of which were unknown ; but objects were collected into groups, 

 characterized by common, external, and obvious signs. From such 

 principles no naturalists except botanists have deviated ; no one has 

 thought of first combining, under the name of animal kingdom, quadru- 

 peds and birds, insects and fishes, reptiles and mollusca, and then of sub- 

 dividing them by the aid of a few arbitrary signs, in such a way that a 

 portion of each should be found in every group — quadrupeds among birds 

 and fishes, reptiles amongst insects and mammalia ; but each great natural 

 group has been confined within its own proper limits. Botany alone, of 

 all the branches of natural history, has been treated otherwise ; and this 

 in modern times. 



The first writers who acknowledged any system departed in no degree 

 from what they considered a classification of plants, according to their 

 general resemblances. Theophrastus has his water-plants and parasites, 

 pot-herbs and forest trees, and corn-plants ; Dioscorides, aromatics and 

 gum-bearing plants, eatable vegetables, and corn-herbs ; and the succes- 

 sors, imitators, and copiers of those writers retained the same kind of 

 arrangement for many ages. 



At last, in 1570, a Fleming, of the name of Lobel, improved the vulgar 

 modes of distinction, by taking into account characters of a more definite 

 nature than those which had been employed by his predecessors ; and 

 thus was laid the foundation of the modern accurate mode of studying 

 vegetation. To this author succeeded many others, who, while they dis- 

 agreed upon the value to be ascribed to the small number of modifications 

 of structure with 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 Tournefort, 

 who wrote in the end of the seventeenth century. At this time the mate- 

 rials of Botany had increased so much, that the introduction of more pre- 

 cision 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 by which what is really known of the 



