39 ° Boodle. — On some points in the 
orientation as described by him comes out wrong, both on 
his earlier and later interpretations, when compared with 
Botrychium l . 
Holle’s paper has been referred to above for the relation 
of roots to leaves. According to his account the lignification 
of the leaf-trace proceeds acropetally, and when it reaches 
the part opposite the young root, it then proceeds outwards 
into the root and upwards in the leaf-trace. This simultaneous 
lignification in the adjacent organs is important physiologi- 
cally for the purpose of conduction to the young leaf ; but, 
as mentioned above, the junction has not always the appear- 
ance of direct continuity. Ifolle 2 also states that, if one 
disregards the fusion of the leaf-traces of the lowest two 
leaves into the solid stele at the base of the adventitious 
plant, the trace of the first leaf is continuous with the bundle 
of the posterior part of the parent-root, while the trace 
of the second leaf is continuous with the bundle of the 
anterior part of the parent-root. This is probably roughly 
correct. 
Van Tieghem’s theory of the monarch root of Ophioglossnm 
vulgatum , as given in his Traite de Botanique 3 , has been 
quoted above, and is that it ^presents a diarch root with 
one phloem-group abortive. 
Rostowzew 4 states that the stem of Ophioglossnm vulgatum 
possesses secondary thickening of very short duration, but 
gives no details, reserving them for a more complete memoir. 
The later paper is written in Russian 5 , and no detailed 
abstract appears to have been published, but there is an 
explanation of the figures in German. None of the illustra- 
tions, however, refer to secondary thickening. There is a 
figure 6 of a transverse section of a young root-stele showing 
1 Van Tieghem, Symetrie, &c., p. 105. 
2 1. c., p. 314. 
s Van Tieghem, Traite, p. 1394. 
4 Rostowzew, 1 . c. (Oversigt), p. 72. 
5 Rostowzew, Beitrage zur Kenntniss der Ophioglosseen ; 1. 1 ' Ophioglossum 
vulgatum ; Moscow, 1892. 
b Plate II, Fig. 14. 
