THE BOTAXY OF THK 1 ATIM. 423 



In examining the Vegetable Kingdom, we observe that the individuals 

 composing it are formed by the Almighty in accordance with a principle 

 of order, as well as a principle of special adaptation. In other works on 

 Botany the structure and arrangements of the various parts of the root, 

 stem, leaves, and flowers of plants, and their different functions will be 

 found. It is our present duty to apply the facts of vegetable anatomy 

 and physiology to the classification of plants, and to consider the plan 

 according to which they are grouped together in classes and families. 



We see around us various kinds or sorts of plants, more or less resem- 

 bling each other or, in other words, more or less related to each other, 

 in Systematic Botany we endeavour to mark these resemblances, and to 

 determine their relations. It is impossible to give a scientific arrange- 

 ment of the plants of the globe without a thorough knowledge of struc- 

 ture, and without an extensive acquaintance with the vegetation of all 

 parts of the world. We cannot expect to determine the system on which 

 plants have been grouped, until we are familiar with all the forms which 

 they present. Hence, in the present state of our knowledge, there must 

 be imperfection in our attempts at systematising. The floras of many 

 regions in Africa, India, China,' Australia, and America, are still unknown, 

 and we may therefore conclude that in all systems there will be gaps, to 

 be filled up as our knowledge increases. Sufficient, however, is known 

 to enable us to group plants according to certain evident alliances. 



The necessity for arrangement is evident, when we reflect that there 



are probably 150,000 known species of plants on the earth. In order to 



make these available for scientific purposes, it is absolutely essential that 



they should be named and classified. In associating plants in certain 



groups, we naturally proceed on an idea of resemblance or likeness. While. 



in ordinary language this idea is vague and indefinite, in scientific langu- 



it must In- strict, and rigorous, It is not enough to say that one plant 



:'>ther in its general aspect, we must ascertain the particulars 



of agreement, and the points in which they differ ; we HUM wci^h well 



importance of the characters, and must compare organs which 

 equivalent in value; ami thus we ^hall often find, that plants whir' 1 



<;rvers appear alike are in reality totally different. Tin- study 

 natomy of plants gives us a strict and aecui 

 age which HP -idly adhered to in classification. 



y OCCUX iii nadir.-, are viewed as individual* reseinl.lr 



ditl' m each other. Some individuals are SO decidedly alike that 



we at on lie 'in the same name. Thus a field of wl> 



d of nuiii'Tniis similar individuals which can be separate- 1 fi 



