22 P. ORPEN BOWER. 
entering the stem, these pairs fuse into single bundles 
(ps, Dd). The xylem of these bundles is turned towards the 
centre of the axis. Each of the two leaves of the plumule, 
whose median planes are at right angles to those of the 
cotyledons, has two main bundles.' As these pursue their 
course downwards, at first they gradually approach the 
centre of the stem (A and B), then curving suddenly out- 
wards, but still approaching one another, they meet and 
fuse (8). Before this sudden curving outwards, a weak 
and irregular branch is given off from each; and the branches 
thus given off from each of the four bundles form a ring, 
which puts the bundle systems of the two halves of the 
plant (right and left as the sections fig. 15 lie) in connec- 
tion with one another. This ring is, however, very weakly 
developed, consisting in parts of only a single series of 
elements. It will probably in older plants be more strongly 
represented. After fusion, as described, the bundles from 
the plumular leaves descend for a short distance as two 
bundles, which soon again divide (B), and each of the four 
branches thus formed passes directly to one of the compound 
bundles, formed by union of two of the cotyledonary bundles; 
they attach themselves to these at their point of junction. 
(s) Immediately below this point, each compound bundle 
thus formed begins to rotate upon its axis. This may be 
traced on comparison of the successive sections of fig. 15; 
the direction of rotation being here indicated by arrows. 
The result is that the bundles of the hypo-cotyledonary 
stem assume the position previously described, the xylem 
being external to the phloem. The diagram (fig. 16) may 
serve to make the course of the bundles just described more 
intelligible. We shall now be able to realise the position 
of the protoxylem with regard to the bundle in the 
hypocotyledonary stem. It is, so to speak, a streamer, 
which lags behiad in the rotation of the bundles on their 
axes. 
As previously stated, the apical papilla, which lies between 
the two plumular leaves, was not observed in the case of any 
seedling to undergo a further development. The figure 17 
represents the apical cone as seen from above, lying between 
the two plumular leaves. The arrangement of cells here 
shown presents no point of special interest. It corresponds 
on the whole with the apex of others of the conifere.’ 
1 Traces are to be seen of a further pair of lateral bundles in each plumula 
leaf, but in none of the plants I have examined were these lateral bundles 
sufficiently developed to admit of their course being followed with accuracy. 
2 Cf. Strasburger, ‘Coniferz,’ pl. xxiii. 
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