NATURAL FAMILIES. 191 



The rose, the pink, and the bell-flower, are regular in their 

 form ; that is, there is a symmetry and equality in their parts. 

 In a regular corolla, if we suppose the point of a compass 

 placed upon its centre, and a circle traced around the edge of 

 the flower, each one of its divisions will just touch the circle. 

 There may, however, be slight inequalities in regular corollas, 

 as in the lily we sometimes see some petals a little longer than 

 the others ; this is an exception to the general rule. 



You must learn to distinguish between rules and exceptions ; 

 it is often owing to a want of this discrimination, that young 

 persons find difficulties in understanding a science ; they con- 

 found the rules and exceptions, thinking, very erroneously, that 

 the knowledge of the one is as important as that of the other. 

 If a clear conception of general rules be established in the mind, 

 the exceptions or variations will be gradually learned as you 

 apply the rules to particular cases. But if you attempt, at the 

 commencement of the study of any science, to learn all the ex- 

 ceptions as well as rules, you will never obtain clear ideas up.' 

 on the subject. 



You will recollect the general rules with respect to regular 

 corollas. Irregular corollas differ so widely from these general 

 rules, that you will be in little danger of mistaking them for ex- 

 ceptions; they constitute, indeed, a different natural family, 

 though according to the artificial method of classification, they 

 may often be placed near to regular corollas. Irregular corol- 

 las are various in their forms ; the papilionaceous, which we 

 are now considering, seem, as they stand upon their stem, to 

 consist of an upper and under part. In examining a natural 

 flower of this kind, a pea for example, you should first observe 

 the calyx ; this is monophyllous, that is, consisting of one entire 

 leaf, ending in five distinct leafy points (See Fig. 100, a); the 

 two upper ones wider than the three under ones. The calyx 

 bends towards the lower part, as also does the peduncle, or lit- 

 tle stalk which supports it. The peduncle is very small and 

 flexible (See Fig. 100,g) ; so that the flower readily avoids a 

 current of air, and turns its back to the wind and rain. 



In examining the corolla you will see that it is polypetalous. 

 The first piece, or large petal, covering the others and occupy- 

 ing the upper part of the corolla, is called the standard or ban- 

 ner. This petal is, evidently, designed to protect the stamens 

 and other parts of the flower, from injuries by the weather. 

 Upon taking off the banner you will find that it is inserted by 

 a little process, or projecting part into the side pieces, so that 



Regular corollas Important to distinguish between rules and exceptions 

 - juar corollas Manner of examining a natural flower of the papilionaceous 



