16 The Natural System. 





they in most cases belong to Octandria. Thus it appears that 

 it is not by means of the Artificial System that the plant is to 

 be discovered, but through its resemblance to other Polygonums, 

 thus applying the very principles of the Natural System. 

 Again, the genus Rhamnus, or Buckthorn, is placed in the 

 class Pentandria, while the most common species, (R. alnifo- 

 lius,) is Dioecious ; so that if, on observing that one individual 

 bears female and another male flowers, it should be sought for 

 in the class Dicecia, the result would be the same as before. 

 These instances are not exaggerated, and similar ones are by 

 no means uncommon. It has been proved that in fourteen 

 divisions of the Linnaean System, including one hundred and 

 seventy-three British genera, the number of such exceptions 

 amounts to forty-three, or nearly one quarter ; and that out of 

 two hundred and seventy-four North American genera, belong- 

 ing to eighteen Linnaean sections, there are no less than seventy- 

 eight exceptions, or more than a quarter of the whole. This 

 comprehends, too, only those variations which are constant and 

 uniform, and not merely accidental deviations. It is true, that 

 the labors of botanists have in a degree lessened the difficulty 

 by pointing out the most perplexing of these variations, in such 

 a manner as to prevent the loss of time and patience in futile 

 endeavors at finding genera in wrong classes, or species in 

 wrong genera ; but this does not lessen the imperfections of the 

 system. 



