STIGMARIA. 



by assuming with Williamson that the collateral bundle has developed a few 

 smaller elements on its outer margin, and that these were not disposed in 

 any regular order, but were often crowded together at the angles. We may 

 even be able to see in them the first beginning of the secondary growth, 

 which, as has been before remarked, is certainly present in some cases in 

 bundles of the second type. And this view even appears to me to be much 

 simpler and more probable than that which Renault has developed. But 

 this author has produced other arguments in support of his opinion. He 

 has figured \he tangential section through the rind of an axis found near 



Autun l , and this contains two transverse sec- 

 tions of traces, one of which is a collateral, the 

 other a triarch stellate bundle. The two are in 

 fact very different from one another. The 

 stellate bundle, which is much macerated, is 

 cut through rather obliquely but shows 

 tracheides with round pits, such as never 

 occur in genuine Stigmariae. The collateral 

 bundle also shows important differences, so 

 that it is more than doubtful whether the 

 specimen belongs to Stigmariae. Yet Renault 2 

 says himself : ' It is possible that this Stigmaria 

 may be the rhizome of Sigillariopsis Decaisnei, 

 which shows in the structure of the wood of 

 the stem a combination of radiate, reticulate 

 and dotted tracheides.' It is obvious that 

 the specimen cannot in these circumstances 

 prove anything in connection with the 

 characters of Stigmariae. Renault next 

 maintains that in examining material from 

 England, which doubtless belongs to Stig- 

 mariae, he has found appendages with a triarch wood-strand, from 

 the angles of which proceed delicate vascular bundles destined for 

 lateral roots, and he has more than once reproduced the preparation 

 which is intended to prove this view 3 (Fig. 35). The specimen shows a 

 wood -strand which in form comes very near to the second type ; but it is 

 only the angle touching the inner cylinder which has the appearance of an 

 initial strand, while this would be a forced interpretation of the other two. 

 The supposed lateral root-bundle connects with the angle which is evidently 

 an initial angle, and the longitudinal view of it shows a single tracheide ; but 

 the nature of this bundle is very doubtful. I was unable to recognise the 



_Fic. 35. Reproduction of Renault's 

 principal preparation proving that the 

 appendages of Stigmaria of the third 

 category are of the nature of roots. At a 

 the place where the lateral root is given off 

 which is supposed to be furnished with a 

 central tracheide. At b the places where 

 Renault thinks that he sees the two other 

 initial strands of his triarch root-bundles. 



1 Renault (10), t. 3, ff. 2, 3, 7. Renault (10), p. 35. 



f. i, and vol. iii, t. A, f. 4 bis, and (10), t. a, f. 8. 



3 Renault (2), vol. i, t. 20, 



