founded on the Structure of their Seedlings . 89 
EXPLANATION OF FIGURES IN PLATES I-VII. 
Illustrating Miss Sargant’s paper on the Origin of Monocotyledons. 
The figures on Plates I and II are drawn by Miss E. Sargant, with the ex- 
ception of Fig. 5 on Plate I (Miss E. N. Thomas). 
The figures on Plates III-VII are drawn by Miss Agnes Robertson, with the 
exception of those marked (E. S.) or (E. N. T.). 
PLATE I. 
Albuca Nelsoni. 
Fig. 1. Outline of whole seedling A 5 , drawn from life. x 1 / l . Outline of 
young bulb and adjacent parts from seedling B u preserved in spirit, x 1 / 1 . 
Fig. 2. From microtome series through seedling A s . Transverse section of 
embryonic stem-bud enclosed in expanded base of cotyledon, x 75. 
Fig. 3. From same series, *16 mm. below Fig. 2. Transverse section through 
transitional region. Each main cotyledonary trace has formed three protoxylem 
groups: px v px iy px. iy and. px iy px 2 ' , px z . x 210. 
Fig. 4. From same series, *12 mm. below Fig. 3. Triarch root forming, but 
original tetrarch structure indicated by presence of protoxylem group px z +pxj. 
X 210 . 
Hyacinthus romanus. 
Fig. 5. Outline of seedling A 5 , from life, x 1 / i . (E. N. T.) 
Fig. 6. From microtome series through seedling A 5 . Transverse section 
through embryonic stem-bud enclosed in expanded base of cotyledon. Two main 
bundles, M lf M 2y and four lateral strands in cotyledon, x 75. 
Fig. 7. From same series, *27 mm. below Fig. 6. Formation of phloem girdle 
indicated. Two lateral bundles, / t , / 2 , unite with main bundles, M ly M 2 , to form 
stele, x 225. 
Fig. 8. From same series, *04 mm. below Fig. 7. The whole xylem of bundles 
l ly l 2 , has joined the lowest group derived from the main bundles, px z +px z . 
x 225. 
Fig. 9. From same series, .13 mm. below Fig. 8. Tetrarch root-stele. The 
last- formed group of protoxylem,/^, is smaller than the others, x 225. 
PLATE II. 
Muscari atlanticum . 
Fig. 1. Outline of seedling A ly preserved in spirit, x 1 / 1 . 
Fig. 2. From microtome series through seedling A±, just below first node. Two 
main cotyledonary traces, M ly M 2 , and two lateral ones, l L} l 2y in stele, x 200. 
Fig. 3. From same series, -03 mm. below Fig. 2. Pentarch root-stele indicated. 
The two lateral traces (/ x , l 2 in Fig. 2) have supplied the lowest phloem group, 
x 300. 
