28(5 DECOMPOSITE ORGANS. CHAP. I. 



may not be true,; so that if any general division 

 arising from internal structure is adopted, it must 

 be instituted on different grounds. 



And if the subject is understood to be exhausted, 

 what are we to say of such genera as are furnished 

 with more than two cotyledons ? Defontaines says, 

 indeed, that they are only dicotyledonous plants 

 after all, but does not offer any satisfactory proof, 

 which if he were even to produce, still there would 

 remain the several tribes of plants that are con- 

 fessedly destitute of cotyledons altogether, which 

 would leave an additional class or division entirely 

 unprovided for, even if we should not, with Dr. 

 Smith, suppose the Date Palm, the very subject 

 of Defontaines' description, to be itself acotyle- 

 donous. 



But this additional class is altogether different 

 in its organization from the other two, exhibiting 

 neither the woody layers of the one, nor the woody 

 fibres of the other; but consisting merely of a 

 spongy, or leathery, and homogenous mass of pulp 

 or slender fibres enveloped by an epidermis, as in 

 the case of many of the imperfect plants ; which 

 cannot however be represented as exhibiting any 

 very strict uniformity of structure throughout, but 

 only such a similarity of mode as may justify an 

 arrangement founded merely on generalities. And 

 hence the ground of a much more comprehensive 

 division of vegetables, as founded on the internal 

 structure. 



