120 TAXONOMY. 



its first appearance, we perceive that it was intended to have 

 been a branch, which has only proved abortive, and which, 

 notwithstanding, even as a spine, bears leaves, and, in Euplior- 

 hia heptagona, sometimes flowers and fruit. 



179. 



2. To avoid mistakes, we also often follow analogy or in- 

 duction. When a form is C(>mmon to several families, we 

 cannot mistake its sign, even when it seems to fail. Thus, 

 as the Orchideae are related to the Scitamineac and Iridea?, we 

 find in the former the sign of the three male organs, in the 

 two lateral appendages of the column of fructification, or the 

 Staminodia of Richard. In like manner, the two fibres, 

 which Gratiola carries beside the fruitful filaments, will ap- 

 peal* to be abortive filaments, when we compare them with 

 the other Scrophulari?e, which sdltnetimes have four fruitful 

 filaments, and sometimes, in addition to these, even a fifth. 



The same analogy which leads us from genus to genus, ex- 

 plains also one species by another. As in the Lcea we con- 

 sider the cleft scales, with which the filaments are inter- 

 mingled, to be abortive filaments, because in the nearly re- 

 lated genus Alelia ten filaments have perfect anthers ; we 

 also conclude that Polijgoiium amphihmm, which has only 

 five, and Polygonum persicaria^ which has only six filaments, 

 have lost the rest by abortion, because several species of tlie 

 same genus possess eight filaments. 



180. 

 From abortion principally arise the many irregularities in the 

 structure of plants ; because we may suppose that the original 

 formation of natural bodies is regular. When we thus find 

 unhnportant irregularities in the organs of a plant, we may 

 suspect that there are plants in which these irregularities as- 

 sume a more marked aspect, — tiiat there are others where 

 these organs are completely a])ortive, — and othei's in which 

 complete regularity takes place. The usual form of the pa- 

 pilionaceous flower is very irregular in D'lmorpha ; th/:," vexil- 

 lum and carina in Amorpha are completely abortive ; and m 



