i 74 Berridge and Sunday. 
EXPLANATION OF PLATES II. AND III. ILLUSTRATING THE PAPER 
BY MISS BERRIDGE AND MISS SANDAY ON “ OOGENESIS AND 
EMBRYOGENY IN EPHEDRA DIET ACHY A." 
a.r , central cell of archegonium ; j.c. jacket-cell ; p.t., pollen-tube ; p.e ., pro¬ 
embryo ; e »., egg-nucleus ; m.u., male nucleus; v.c., ventral canal nucleus. 
Fig. 1. Tetrad of megaspores; >//., functional megaspore, x 360. 
Fig. 2. Longitudinal section of young ovulate strobilus. n , nucellus ; i., 
integument ; o.c., outer envelope ; b , bract. 
Fig. 3. Longitudinal section of female “ flower.” e.s , embryo-sac ; a., arche- 
gonial region ; a., nucellus ; i., integument ; o.r., outer envelope. 
Fig. 4a. Young archegonium with primary neck-cell (»). 
Fig. 4b. Tubular cell dividing into a series of jacket-cells. 
Fig. 5. Sister archegonia probably derived from a single archegonium initial, 
x 98. 
Fig. 6 Fully developed necks of two unfertilized archegonium. d., products 
of degeneration of neck cells, p.ch., pollen-chamber, x 174. 
Fig. 7. Apex of archegonium with egg and ventral canal nuclei separating 
amitotically. 
Fig. 8. (a) Small archegonium, (b) jacket cell, showing the resemblance of the 
egg and ventral canal nncleus in (a) to the pair of nuclei in (b). 
Archegonium (a) is one of a pair of sister archegonia similar to 
those shown in Fig. 5. 
Fig. 9. Ephedra fragilis. Ventral canal cell cut off from the apex of an 
archegonium. x 300. 
Fig. 10. An archegonium, the apex of which has grown upward to meet the 
pollen-tube, a , original position of the apex, x 120. 
Fig 11. A pollen-tube within the apex of an archegonium. />.»., five small 
nuclei discharged from the pollen-tube, x 300. 
Fig. 12 Male nucleus approaching the egg nucleus, x 300. 
Fig, 13. A pair of male gametes; the functional gamete (f.g.) leaving the 
cytoplasmic sheath. x600. 
Fig. 14. A fertilized archegonium with normal pro-embryonal cells in its 
pointed base, x125. 
Fig 15. Pro-embryos, a and b show the first division of the nucleus ; c. 
shows a two-celled embryo, and appears to have arisen from a jacket 
cell ; d. is multi-nucleate, and also arises from a jacket cell. x300. 
Fig 16. An archegonium containing both normal and abnormal series of pro 
embryonal cells, x 130. 
Fig. 17. Jacket-oell nuclei escaping into the archegonium of Fig. 17 and 
fusing to form a pro embryonal cell, x 236. 
Fig. 18. Pro-embryonal cell formed by the outgrowth of a jacket cell belonging 
to the wall of the archegonium. x 360. 
pig i 9 Pro-embryonal cell formed within a jacket cell, e., endosperm cells : 
a., degenerating archegonium. x300. 
Fig 20. Migration of jacket nuclei, x 300. 
pig. 21. Nuclear spindle within a jacket cell. «., remains of second nucleus of 
the jacket cell; c., neighbouring cell from which the nucleus has 
migrated. 
