XX1Y PRELIMINARY DISCOURSES. 



stages of metamorphosis, from their origin to their end from seed 

 to seed again. 



DISCOURSE IV. 

 Classification of Plants. Artificial and Natural Methods. 



HAVING seen that the external organs of Plants consist, funda- 

 mentally, of those appendages called leaves, which are regularly 

 modified, and prepared for their several functions, at the successive 

 stages of the vegetable career, we shall now proceed to notice 

 some of the Methods, by which Naturalists have proposed to facilitate 

 a more extended and particular acquaintance with the different 

 kinds: i. e. with the Genera, and Species, of the vegetable king- 

 dom. Although the organs of the various tribes assume an almost 

 endless variety of forms, and aspects and even in the same species, 

 are subject to considerable modification, by the influence of culture, 

 soil, climate, and other circumstances, it has been observed, never- 

 theless, that the peculiar structure, and essential character, of each 

 particular family, are remarkably constant, and well defined. Even 

 the monstrosities produced by long culture, disease, or other accident, 

 usually retain enough of their primitive features to enable us to 

 recognize them, under all their disguises. It is this constancy, or 

 permanence of character, which affords the basis of all classification ; 

 and classification, or the grouping together of kindred individuals, is 

 the apparatus by which our conceptions of objects are so arranged, 

 and fixed, as to secure a comprehensive general view, while it 

 facilitates all subordinate and detailed investigations.* 



The most important, or conspicuous organs of plants their most 

 constant and characteristic features whether consisting in the struc- 

 ture, the presence, or even the absence, of particular parts, have 



*It would be impracticable, without the machinery of classification, to make any 

 important advances in Natural knowledge, or to leave any durable traces of 

 our progress, in such knowledge, for the benefit of those who come after us. To 

 use a nautical term, we must bday all the information we acquire, if we wish to 

 render it permanently available to others : and the best belaying fixtures, to pre- 

 vent entanglement and confusion in Natural History, will be found in the most 

 lucid and practical systematic arrangement. " Omnia " says LINNAEUS " quae a 

 nobis vere dignosci possunt, dependent a CLARA METHODO, qua distinguimus similia a 

 dissimitibus." 



