2C,0 



STfGMARIA. 



On the other hand, we know that the trace-bundles, wherever they are 

 examined, are found to originate on the inner margin of the wedges of wood 

 in the axis of Stigmariae, that their basal portion runs through the primary 

 rays and grows in thickness pari passu with the neighbouring wood. 

 If then so many late-formed adventitious members as Renault supposes 

 really appeared on these axes, we should expect to find their trace-strands 

 somewhere or other, though they could not of course have made their 

 way so far as the inner margin of the ring of wood. But no one has yet suc- 

 ceeded in finding them ; and if the plant was capable of forming normal roots 

 as organs of absorption, it must seem a surprising piece of luxury that it 

 should at the same time have leaves adapted to the same function. 

 Functional adaptation of certain organs to supply the place of others that 

 are wanting is a frequent phenomenon, but I know of no analogous instance 

 of such a biological arrangement as is here described. 



It will be apparent from the above remarks that, until proof to the 

 contrary is forthcoming, I must hold to the opinion that all appendages 

 are members of the like morphological character. It matters little whether 

 they are supposed to be roots or leaves, and it would perhaps be well to 

 avoid any such precise definition of ideas in the case of organs, which have 

 no direct analogues in the whole of our recent vegetation. 



Besides his ' stigmarhizomes,' of which we have hitherto been speaking, 

 Renault considers that he has found Stigmariae which were real roots, being 

 supposed never to have borne foliar appendages at any time, but always 

 only root-appendages. These are his ' stigmarhizes,' of which however he 

 has so little to say that he dismisses them in less than the space of a page 

 of his monograph l , while he devotes fourteen pages to the description of 

 the rhizomes. The only figure of the transverse section of a ' stigmarhize ' 

 which the work contains is taken from a fragment from Autun 2 ; and the 

 anomalies in structure which it exhibits, and for which the original should 

 be compared, make me think that it can hardly be a Stigmaria at all. As 

 even Renault's reply 3 to Williamson's and Hartog's objections affords no 

 better explanation of the whole matter, we are compelled to ask what it 

 was that suggested to him the idea of these ' stigmarhizes.' The further we 

 search into the literature, the more we shall be convinced that the scanty 

 array of facts which it supplies can scarcely by itself have given occasion 

 to it. The truth is that the theory of ' stigmarhizes ' rests entirely on certain 

 views of Grand' Eury which appeared in his first work 4 , and which he 

 subsequently carried out still further 5 . Grand' Eury attempted to distin- 

 guish the entire group of fossils which we are considering into two genera, 



1 Renault (W), p. 35. 2 Renault ',10), t. i, f. 14. * Renault (2\ vol. iii. Introd. 



4 Grand' Eury (1\ p. 166. 5 Grand' Eury (2\ p. 150. 



