lb TRANSACTIONS. NATURAL HISTORY SOCIETY OF GLASGOW. 



theory, and figures the specimen on which it is based, but it 

 does not really support his contention. 1 The real proof that 

 Stigmaria is a rhizome rests on altogether different grounds. 



In 1877 Grand 'Eury distinguished two forms of Stigmaria — 

 true Stigmaria and what he named Stigmariopsis. 2 The dis- 

 tinctive characters given by this botanist were quite insufficient 

 for their separation, though subsequent investigations have shown 

 that Stigmai*iopsis is essentially distinct from Stigmaria, and, 

 though little is yet known of the genus, it cannot be united with 

 Stigmaria. S.tigmariopsis will be considered presently. 



Renault, :J influenced perhaps by the investigations of Grand 

 'Eury, advocated strongly a dual nature in Stigmaria. Some 

 Stigmaria he regards as roots, others as rhizomes, and some 

 Stigmaria he believes have root leaves and rootlets on the same 

 organ. The evidence on which Renault formed this opinion is 

 the structure of the vascular bundles which go to the appendicular 

 organs, by wdiatever name these may be called. The evidence 

 he relies on in support of this view appears to rest on a misinter- 

 pretation of the structure of the bundle which enters the 

 appendicular organs. The question resolves itself into whether 

 the bundles are monarch (Collateral) or triarch, or whether some 

 are monarch and others triarch on the same rhizome. Williamson 

 and Solms-Laubach believe they are monarch (Collateral) — and 

 Renault some monarch and some triarch. 



Among the rootlet bundles — for such I believe the appendicular 

 organs to be — several slight modifications of form and arrange- 

 ment of the vessels can be observed, and Solms-Laubach distin- 

 guishes three types. 4 In extreme cases these three forms are 

 tolerably distinct, but they run into each other. That variations 

 in minor details will occur in the form of the bundle is to be 

 expected, when we remember that Stigmaria is not only the 

 rhizome of several species, but even of different genera. 



In certain bundles, like fig. 12, we see at (a), according to one 

 view, the primary strand of the bundle to which additions have 



1 Goppert, I.e., Pi. XXXV., fig. 3. 



- Grand 'Eury, Flore carbon, du Depart, de la Loire et du Centre at la 

 France, pp. 166 and 171. 



s Renault, Court d. butan. fos8., Vol. I., p. 159. 1881. 

 * Solms-Laubach. Fossil Botany, p. 276, fig. 34. 



