646 
Kershaw . — Ovule of Bowenia spectabilis. 
some cases the bundles of the inner series pass beyond the level of the origin 
of the integument, into the free portion of the nucellus. 
6. There is held to be a close agreement of the general structure of the 
ovule of Bowenia with seeds of the Medulloseae. 
Cryptogamic Research Laboratory, 
Manchester University. 
March , 1912. 
EXPLANATION OF FIGURES IN PLATE LXI. 
Illustrating Miss Kershaw’s paper on the Ovule of Bowenia spectabilis. 
Fig. 1. Mother-cell of the embryo-sac surrounded by cells of sporogenous tissue, x 150. 
Fig. 2. Mother-cell of the embryo-sac just before the reduction division, x 150. 
Fig. 3. Mother-cell of the embryo-sac divided into three cells, the lowest being slightly larger 
than the others, x 150. 
Fig. 4. Three divisions of the mother-cell of the embryo-sac, the lowest being much larger than 
the other two. x 1 50. 
Fig. 5. Embryo-sac cell with two nuclei, and the degenerating sister cells above, x 150. 
Fig. 6. Embryo-sac with free nuclear division proceeding, x 150. 
Fig, 7. Apex of the nucellus of an unpollinated ovule of size represented in Text-fig. 4, showing 
the median strand of cells which later break down to form the pollen-chamber, x 70. 
Fig. 8. Portion of embryo-sac and surrounding sporogenous tissue from a similar ovule. The 
sporogenous tissue is reduced to a few layers of scattered cells round the embryo-sac, which has a thin 
lining of protoplasm containing the free nuclei, x 150. 
Fig. 9. Sporophyll from a pollinated cone bearing two ovules. Natural size. 
Fig. 10. Transverse section of a vascular bundle of the outer series, showing collateral structure 
and mesarch protoxylem. x 200. 
Fig. 1 1 . Micropylar region of old ovule, showing the relation of upper and lower pollen-chamber 
to the micropyle. The stone layer of the integument is seen, and also the sclerized cells immediately 
surrounding the micropyle. x 30. 
Fig. 1 2. Section from an old ovule at the level where nucellus and integument become free. 
The terminal tracheides of a vascular bundle of the inner series are seen to run for a short distance 
into the free portion of the nucellus. int. = integument ; nuc. = nucellus. x 200. 
Fig. 13. Transverse section of a vascular bundle of the inner series, showing the concentric 
structure and mesarch protoxylem. x 200. 
Fig. 14. Section of the apex of the nucellus from an old ovule, showing the beak-like upper 
pollen-chamber, and the lower pollen-chamber with a developing pollen-grain, and pollen-tube cut 
obliquely. 
Fig. 15. Apex of the nucellus of an old ovule with five pollen-grains developing in the lower 
pollen-chamber, two of which show the complete apparatus with central generative cell (g) and 
two prothallial cells (p x and p 2 ). In two cases one of the pair of blepharoplasts is seen, x 100. 
Fig. 16. Central cell showing a large nucleus with single nucleolus and a pair of blepharoblasts. 
x 300. 
Fig. 17. Neck cells of an archegonium from an old ovule, in transverse section, x 150. 
Fig. 18. Median longitudinal section of apex of archegonium, with central cell and nucleus. 
Close to the nucleus are two small masses of a similarly staining substance, x 1 50. 
Fig. 19. Portion of central cell of archegonium with the surrounding pitted membrane and 
jacket layer. Haustoria-like processes of the egg pass into the pits which show no closing membrane, 
x 300. 
Fig. 20. Archegonium of young abnormal ovule with central cell and nucleus, x 150. 
Fig. 21. Apex of nucellus of young abnormal ovule, showing narrow beak -like upper pollen- 
chamber (; u.p.c .) and the larger and wider lower pollen-chamber (l.p.c.). x 60. 
