136 



TAXONOMY, 



From these considerations it follows, that in the theory of 

 classification all these irregular forms must be traced back 

 to their regular primitive form, even although this should be 

 of but rare occurrence. If we compare the Solaneae with the 

 Personatae, the latter appear, from the irregularity of their 

 flowers, and the unequal number of their filaments, to be 

 completely distinguished from the former. But if we exa- 

 mine the fruit, the placentation, the situation of the embryon, 

 and the other relations of the flower, we find the greatest 

 agreement, and the transitions from Nicotiana to Hyoscya^ 

 mus^ to Verbascum, and to Celsia, strike every person ; for 

 in Verbascum the lobes of the corolla are often irregular, and 

 the filaments of unequal length. If we change but one fila- 

 ment in Verbascum, it becomes Celsia. 



In general, we must observe, that an irregularity of parts 

 seldom appears in one organ, without being also apparent in 

 others. But the fruit is frequently an exception to thi§. 



205. 



The unequal length of the filaments is nevertheless some- 

 times connected with perfect regularity in the other parts, of 

 which we see daily instances in Phlox and Oxalis. Another 

 law prevails here, namely, that the parts of a system are un- 

 folded successively, and not at once. Hence in Phlox in par- 

 ticular, there are some only of the filaments which have the 

 necessary length for enabling the anthers to impregnate the 

 stigma. In Oxalis, there is more regularity, because exact- 

 ly one half of the filaments is longer than the other half. 



206. 



'With respect to the connection of parts, the rule is, that 

 all organs which are united with their supports are persistent, 

 and all those which loosen themselves at their base are deci- 

 duous. In like manner, related parts, which have a suture, 

 open themselves ; whilst those which liave no suture remain 

 shut. With respect to the internal structure of parts, we 

 find that the interruption of continuous structure arises for 



