STIG MARIA. 289 



moreover, the distinct formation of buds, the hyponasty and epinasty of 

 which would also be something quite unheard of in the case of roots ; and it 

 may be remarked by the way that this formation of buds proves to my mind 

 that the Stigmariae were exclusively adapted to a soft pulpy environment, 

 for this would be unsuitable and almost impossible in solid ground. 



The latest elaborate examination of the question which we are con- 

 sidering has come from the pen of Renault 1 . He, too, takes Schimper's 

 view, and regards the greater number of Stigmariae at least the exceptions 

 will be noticed presently as rhizomes. He differs from him to the extent 

 of distinguishing the appendages into two classes, one of leaves, the other 

 of adventitious roots. This distinction he rests entirely on the differences 

 in anatomical structure described above on p. 276. I have, however, already 

 shown that these differences may very well be interpreted in a different manner. 

 There are absolutely no external characters present, which could serve for 

 this distinction into leaves and fibrous roots ; and when Renault 2 says: ' In 

 the cortical region the number of bundles belonging to roots becomes 

 greater because the roots are to a great extent of later formation than the 

 cylinder of wood ; their late appearance gives rise to supernumerary spirals, 

 or to scars irregularly distributed on the surface of certain specimens,' it 

 appears to me that this short sentence, which has no particular promin- 

 ence in the text and really contains two unproved assertions, is the Achilles' 

 heel of the whole argument. First of all, specimens with ' supernumerary 

 spirals ' are supposed to have been unusually abundant. For Renault 

 assumes as a necessary consequence of his view, that the portions of a 

 shoot which have appendages with the character of leaves come from 

 the immediate vicinity of the apex, that those which bear roots only 

 belong to the older lower part of the shoot which has lost its leaves, 

 while the portions which are furnished with both kinds of organs repre- 

 sent a middle region. And then it must be assumed that the older 

 portions of rhizomes must be more abundant in the fossil remains than the 

 youngest. Now all Stigmariae, as far as I know, exhibit essentially the 

 same regularly quincuncial arrangement of the scars. I have never been 

 able to see anything of the ' supernumerary spirals ' and other irregularities, 

 though I have examined a great many specimens and figures for this purpose, 

 nor have I seen any specimens in Renault's collection which prove the 

 point. In the sections tangential to the surface of a Stigmaria which he 

 has figured :J , and which pass through both kinds of organs, there is no 

 certainty that all the sections are really sections of the same axis. In the 

 transverse section 4 the 'root' marked c certainly does not belong to the 

 specimen, but is merely a later introduction. 



1 Renault (2), vol. i, and Introd. to vol. iii, and (10). 2 Renault (10), p. 23. 3 Renault 



(10), t. I, ff. 3 and 7. * Renault (10), t. I, f. i. 



U 



