28 q Boiver. — Notes on the Morphology of 
vascular strands of the leaf-traces, which at first sight appear indefinite in 
position. But comparison with the diagrammatized drawing in Fig. 4, in 
which the roots are omitted, shows that the scheme above described is 
adhered to. There is a central pith of moderate dimensions, round which 
are disposed three meristeles with their xylems directed inwards, and sepa- 
rated by wide foliar gaps. On either side of one of these gaps the two 
distinct strands of a leaf-trace (No. 1) are coming away, but not yet 
detached. In the case of No. 2 one of the strands is detached, but the 
other is still connected with the meristele of the axis. In leaf-trace No. 3 
both strands are clear, while that on the anodic side is already branched. 
It may be noted that constantly the anodic branch takes precedence in 
time, and is also the larger of the two. Following on through the succes- 
sion of leaves — which incidentally it may be remarked show no exact 
regularity of divergence— -the strands become wider and wider apart, owing 
to parenchymatous swelling, and break up into a number of strands, which 
behave after the manner already shown in Fig. 2. 
This being the condition in an old stock, it became a matter of interest 
to see what is the vascular arrangement in those young buds formed upon 
the roots, which in default of the seedling plants may be taken as giving 
evidence of the ontogenetic history. The roots correspond to those of 
other species of the genus, in growing with a single initial cell, and in 
showing frequent dichotomy. On these, close to the apex, the adventitious 
buds arise endogenously. The details, so far as they have been observed, 
correspond to what has already been demonstrated by Rostowzew 1 for 
O. vnlgatum . The bud soon swells into an almost spherical tuber, which 
shows at first little differentiation, but as it grows a deep indentation 
becomes apparent, lined with closely grouped hairs. At the base of this is 
the punctum vegetationis which gives origin to the young leaves. The first 
of these is shown emerging from the terminal tuft of hairs in Fig. 1, B. 
Sections through such tubers show at first little differentiation of the 
turgid parenchymatous mass, but as the leaf formation is advanced the 
vascular system develops, and in a case where several leaves were already 
initiated the condition was traced from below upwards, with the results 
shown in Fig. 5, I-VIII. The vascular system of the bud is inserted upon 
that of the root from which it sprang. From the first the stele of the bud 
was in this case distinctly medullated, though it does not appear to be 
always so. Fig. 5, I, shows it at the level of its attachment to the vascular 
tissue of the root, the tracheides projecting right and left forming the junc- 
tion with it. Externally the stele is delimited by a definite endodermis ; 
the xylem is, however, only poorly developed, and the phloem is hardly 
recognizable as such. This condition is continued upwards (II), but shortly 
the continuity of the xylem-ring is broken by a gap, which resembles the 
1 Recherches sur V Ophioglossum vulgatum , L., Copenhagen, 1891, p. 12. 
