differences in the Structure of Stems, 239 



at the corresponding place in the next succeeding cell. It is 

 only since the autumn of 1837 that I have submitted this pro- 

 cess to a proper radical research^ and must beg to correct every- 

 thing that I formerly said in ' Miiller's Archiv^, 1838*' (Con- 

 tributions to PhytogenesisJ in accordance with my views at 

 that time respecting the origin of cambium, although in the 

 explanation I have there given o{ the function of woody stems 

 no essential alteration is requisite. 



This difference between limited and unlimited vascular 

 bundles affords the 07ily universal distinction between Mono- 

 cotyledons and Dicotyledons. In the annual Dicotyledons 

 the vascular bundle, checked in its further development by 

 the death of the plant, has, it is true, in so far some similarity 

 to the Monocotyledons ; yet, with close research, the difference 

 is distinctly apparent, for the formative layer constantly re- 

 tains to the last moment its generating power; and upon 

 this, in fact, is founded the lignification of annual plants, 

 arising from a consequent prevention of the flowering, e. g., 

 in Reseda odorata and Cheiranthus annuus. For those who 

 find an advancement of science solely and wholly in the em- 

 ployment of new terms, and who are tired of the good old 

 division into Monocotyledons and Dicotyledons-^, I propose, 

 instead of the nonsensical division into Endogens and ExogenSy 

 the denomination of Teleophytes for Monocotyledons, and 

 Synechophytes for Dicotyledons, founded on the preceding 

 observations. 



2. The second distinction among the various organiza- 

 tions of stems, is founded on the number and arrange- 

 ment of the vascular bundles, namely, whether only one 

 simple circle, or several concentric circles, are present. In 

 the first case they generally approach sooner or later close to 

 each other, and thus form a hollow closed cylinder, which is 

 only traversed by greater or smaller bands of the compressed 

 parenchyma, from within outwards: these bands are called 



* A translation of this Memoir appeared in the 6th Part of Taylor's Scien- 

 tific Memoirs, selected from foreign transactions, &c. Edit. 



f This division, nevertheless, remains the only correct one, because it 

 depends on the development; and its value is not even lessened by some of 

 the ConifercB, since the essential character consists not in the number, but in 

 the verticillation of the cotyledons. 



