SECT. I. ORGANOGRAPHY AND GLOSSOLOGY. 67 



be " toothed ;" that of b, which has the indentations 

 deeper, is called "divided/' or "incised;" and c is 

 termed " partite." Where the 

 limb is almost severed into se- 

 parate segments, each portion, 

 when tolerably large, is also termed 

 a "lobe," and the angle at which 

 the lobes meet is the " sinus." ) 

 When the teeth are large and 

 regular, they are termed " ser- 

 ratures ; " and when these are 

 rounded, ." crenations." Thus, 

 a vast number of terms, most of a b c 



them of very simple construction, and easy compre- 

 hension, are used, for expressing a variety of different 

 modifications, by which these and other organs of planst 

 may be accurately defined. 



The leaves on different parts of the same plant often 

 differ in shape ; and even those on the same part are 

 sometimes subject to great modifications, according as 

 they are influenced by the peculiar circumstances under 

 which they are developed. Thus, we may occasionally 

 find three varieties, among the radical leaves on the same 

 plant of horse-radish (Cochlearia armoracia), where the 

 marginal indentations vary as much as in fig. 63. In ge- 

 neral, however, the leaves of the same plants, or at least on 

 the same parts of a plant, retain a sufficient constancy 

 in their character, to enable us to use them for the pur- 

 pose of discriminating between species which are very 

 closely allied. It would not be in character with 

 our present undertaking, to enter more minutely into 

 any description of the forms of leaves ; but we recom- 

 mend all who wish to pursue this subject further, and 

 to become acquainted with those technicalities of the 

 science which are necessary for the purposes of accurate 

 description and descrimination of species, to notice the 

 dependence which the forms of leaves possess upon the 

 conditions of their venation. In the first place, they 

 should remark the general contour of the limb, without 

 F 2 



