476 
EDWARD F. WOODCOCK 
Fig. 14. Polygonella articulata, showing the embryo in the octant st-age sup- 
ported by the characteristic long suspensor; endosperm in fret nuclear condition; 
X 31- 
Fig. 15. P. articulata. A little later stage in which the endosperm has become 
cellular except for the haustorium-like structure at the basal portion; embryo im- 
bedded in the cellular endosperm; X 31. 
Figs. 16 and 17. P. articulata. Successive stages in which the cotyledons 
have become well developed and the embryo sac practically filled with cellular 
endosperm; nucellar tissue reduced; X 31. 
Fig. 18. P. articulata. Mature seed, showing cotyledons in section; aleurone 
layer, starchy endosperm, broken down nucehar tissue, and haustorium-like structure 
present; dotted line indicates plane of cross-section shown in fig. 19; X 31. 
Fig. i8a. Polygonella articulata, showing detailed structure of micropylar 
portion of seed at stage shown in fig. 18; aleurone layer differentiated into a depleted 
and non-depleted region; starchy endosperm packed full of starch grains; X 163, 
Fig. 19. P. articulata, showing position of cotyledons in the seed; dotted line 
indicates plane of longitudinal section shown in fig. 18; X 14. 
Fig. 20. Rheum Rhaponticum. Mature seed; starchy endosperm and aleurone 
layer present; remains of nucellar tissue present at base of seed; dotted line indicates 
plane of cross section shown in fig. 21; X 14. 
Fig. 21. R. Rhaponticum, showing position of the embryo in the seed; dotted 
line indicates plane of longitudinal section shown in fig. 20; X 14. 
Figs. 22-24. Rumex crispus, showing successive stages in the germination, in 
which the radicle of the young seedling appearb through a rent in the micropylar 
portion of the seed and is clasped by the enlarged aleurone layer which appears 
outside the seed coat; X 20. 
Fig. 25. Fagopyrum esculentum, showing an early stage in germination; X 14. 
Fig. 26. F. esculentum. Cross section of seed at a stage somewhat later than 
that lepresented by the preceding figure; X 31. 
Fig. 27. F. esculentum. Late stage in germination; seed remains almost ready 
to drop off the cotyledons; X 14. 
Figs. 28 and 29. Polygonella articulata. Successive stages in germination; 
enlarged micropylar porcion of the aleurone layer appears oucside of seed coac and 
clasps the young seedling; X 31. 
Figs. 30 and 3 1 . Polyg. mum scandens. Successive stages in germination similar 
to those of Rumex crispus shown in figs. 23 and 24; X 14. 
