90 Sargant . — Theory of the Origin of Monocotyledons 
Muscari armenaicum. 
Fig. 4. Outline of seedling A 3 , drawn from life, x' l / x . 
Fig. 5. From microtome series through seedling A 3 , at base of first node. The 
lateral trace l 3 is inserting itself on l x . The two main traces, M x , M 2 , are 
united by the common protoxylem group, px 2 +px 2 . x 200. 
Fig. 6. From same series, .07 mm. below Fig. 5. Pentarch root-stele indicated. 
The lateral traces supply the two lower phloem groups and the protoxylem group 
between them, px 5 , with part of two others. x 300. 
Fig. 7. Outline of seedling A 5 , drawn from life, x 1 / x . 
Fig. 8. From microtome series through seedling A h , just below first node. Two 
main cotyledonary traces, M x and M 2 , and two lateral ones, l x , l 2 . x 200. 
Fig. 9. From same series, -07 mm. below Fig. 8. Tetrarch root-stele indicated. 
The lateral traces (l x , l 2 , in Fig. 8) form half the stele, supplying the two lower 
phloem groups — which are sensibly smaller than the upper ones — the whole of 
the protoxylem group px 5 , and part of groups px 3 and pxj. x 300. 
PLATE III. 
Fritillaria imperialis. 
Fig. 1. Outline of seedling A x , drawn from life, x 1 / 1 . 
Fig. 2. From microtome series through seedling A x . Transverse section through 
enlarged base of cotyledon, enclosing young stem-bud. Two massive bundles, 
M x , M 2 , in cotyledon : three strands in first leaf, x 66. 
Fig. 3. From same series, -32 mm. below Fig. 2. First node. Two plumular 
traces are inserted on M x , M 2 . One branch from the protoxylem of M L goes to 
meet the nearest plumular trace ; the other forms part of the group px 2 at the top 
of the section. The protoxylem of M 2 divides in the same way. x 200. 
Fig. 4. From same series, -18 mm. below Fig. 3. Insertion of plumular traces 
is completed. The xylem group of M L and M 2 are each crescent-shaped. The 
protoxylem of each crescent covers its convex outline : the concavity is occupied 
by a compact phloem group, x 133. 
Fig. 5. From same series, -03 mm. below Fig. 4. Protoxylem crescents broken 
into two groups, px 2 ,px 3 . The structure is that of a diarch root with two thin 
plates of protoxylem extended tangentially, x 133. 
Fig. 6. From same series, *15 mm. below Fig. 5. Phloem in four groups: 
protoxylem breaking up into four too. Tetrarch root-stele indicated, x 133. 
PLATE IV. 
Chlorogalum pomeridianum. 
Fig. 1. Outline of seedling A/, preserved in spirit, x 1 / 1 . (E. N. T.) 
Fig. 2. From microtome series through seedling A 3 ', just above first node. 
Double cotyledonary trace M x + M 2 with three protoxylem groups, px X) px 2 ,px 3 . 
Single plumular trace, which divides as it approaches cotyledonary trace into two 
branches, Pl x , Pl 2 . x 250. (E. S.) 
Fig. 3. From same series, .02 mm. below Fig. 2. Phloem masses above and 
below xylem. Four protoxylem groups, of which px / is plumular. Diarch root- 
stele is suggested, x 250. 
Fig. 4. From same series, .10 mm. below Fig. 3. Tetrarch root-stele, x 250. 
