NATURAL AND ARTIFICIAL SYSTEMS. 99 



possess scarcely any property in common with each other. On 

 this principle we might class plants according to the variations 

 observed in the form and structure of the leaves, or of the corolla 

 of the flower, or any other organ ; but by proceeding in this way, 

 we should learn almost nothing in relation to the organization of 

 these beings, or in respect to the degrees of resemblance or dis- 

 similarity they possess. 



4. A natural method or classification is, on the contrary, a 

 sort of synoptical table of all the modifications that nature has 

 produced in the conformation of plants, a table in which these 

 modifications are arranged according to their relative importance, 

 and serve for the establishment of divisions and successive sub- 

 divisions. In consequence of this, plants arranged according to 

 this method have more important and more numerous points of 

 resemblance to each other in proportion to their approximation to 

 each other in the classification ; for instance, when two plants are 

 placed in two different divisions, it is because they differ from 

 each other in more respects than either of them differs from all 

 the other plants with which it is arranged, and these differences 

 are less important between different species of the same geius 

 than between the different genera of the same family. Those 

 characters which distinguish the families from each other are, in 

 their turn, of less importance than those employed to separate 

 from each other the groups formed by the union of several of 

 these families, and so on. By the assistance of these methods 

 we determine the name of a plant we wish to know with less 

 facility than by an artificial system, but we acquire much more 

 important knowledge, because, having thus ascertained the place 

 a plant occupies in a classification of this kind, we know the 

 principal features of its mode of organization, and consequently 

 its physiological history also. 



5. Botanists have successively employed different artificial 

 systems and the natural method in the classification of plants. 

 Among the first, there is one which, from its simplicity, and the 

 celebrity it for a long time enjoyed, merits being cited here; it is 

 the System of Linnaus (a Swedish botanist who died in 1778), 

 which is based upon the differences that plants present in the 

 various essential parts of their flowers, but especially in their 

 stamens. 



6. In this system of classification plants unprovided with 

 stamens and pistils form a particular class, and those which pos- 

 sess these organs are divided : first, according to the existence of 

 stamens and pistils in the same flower, or in different flowers , 



4. What is meant by the natural method? 



f>. Which method or system of classification is employed by botaniuts ? 



fi Upon what principle is the artificial system of Linnaeus based ? 



