356 PEOFESSOR TV. C. WILLIAMSON ON THE PLANTS 



nothing is more probable than that they should at first be 

 confounded with one another, especially since the carbon- 

 ized condition in which these terminal twigs occur, has led 

 to the disappearance of all internal structure. But for this 

 disappearance nothing would have been easier than the 

 identification of the missing organisms, owing to tliick spix-al 

 vessels of the one group of plants being so very different 

 from the glandular pleurenchyma of the other. 



Tlie existence of a plant with a discoid pith at so early a 

 period as the carboniferous epoch, is a fact of considerable 

 interest to the phytologist. It affords new evidence of the 

 unity of the great plan upon which the Creator has acted 

 from the beginning of time. By varying the combinations 

 of a few elementary tissues, lie has produced all the mar- 

 vellous forms of vegetable life which have constituted the 

 Flora of both the present and the past. It is very question- 

 able whether the modern era has witnessed the creation of 

 a single new tissue, or even the disappearance of a pre- 

 existing one. To this, Sternbergia is no exception. That 

 a peculiar form of pith, which is now found only in a few 

 Jasmineaceas from India, and in the widely different Jug- 

 landaceje of Cashmere and North America, should find a 

 prototype amongst the Coniferas of the primeval world, is 

 a curious circumstance. 



It is manifest that the genus Sternbergia, as adopted by 

 Artis and his successors, exists no longer. Some of its 

 forms having been already assimilated to I^epidophloios, by 

 M. Corda ; and the most characteristic of those which were 

 left being now identified with Dadoxylon — there remains 

 little or nothing to be represented by the name. At all 

 events, Sternbergia approximata may henceforth stand as 

 Dadoxylon approximatum; whether or not all the species of 

 Dadoxylon have possessed this form of pith, is immaterial, 

 since it will not affect the integrity of the genus as defined 

 by M. Brongniart, any more than the similar want of it 



