AND AFFINITIES OF STEPHANOSPERMUM. 399 
epithelioid lining of the sclerotesta (e.¢.) and nucellar epidermis (n.e.). s.t., sclerotesta ; 
l.p., long palisade-cells of this layer adjacent to the entering bundle; m.w., retracted wall of 
macrospore. x 65. S8s. (See p. 365.) 
Figs. 22, 23, and 24. Cells from the sclerotesta showing admirable “ cytological ” preservation. Fig. 22 
. 26. 
. 29. 
. 90. 
. 91. 
represents the adjacent ends of two cells from one of the deeper-lying layers: the paired 
convergent processes on either side. of the transverse wall resemble the protoplasmic 
processes occupying the Dis: in the spindle-shaped enlargements nuclei are present. 
Fig. 23, one of the shorter cells from the second layer of the sclerotesta. Fig. 24, a palisade- 
cell with nuclear vesicle (».) and spirally twisted protoplast. At the inner extremity are 
two pit-processes (p.); at the surface one of the broad conical vacuole-like structures (r.) 
so commonly found in this position. Cf. fig. 4. x 400. S 8m. (See p. 365.) 
. Tangential section through the palisade-layer of the sclerotesta. The middle lamella and 
thickening layers of the wall are shown, and in a few of the cells the thread-like protoplasts 
as dots in the cell-cavities. x 200. S 194. (See p. 365.) 
Tangential section through the epidermis of the nucellus, showing three cells with the 
characteristic carbonised contents. At the top of the figure the section traverses the 
tracheal mantle, portions of two of these elements being represented. x 240. S Qc. 
"o 
. Two of the short and rather irregular tracheides from the tracheal dise shown in fig. 21. x 550. 
S85. (See p. 367.) 
. A small portion of the tracheal mantle where the elements are somewhat isolated as they pass 
into the supra-archegonial gap. They are from the same specimen as fig. 9. x 285. 
S 9c. (See p. 369.) 
Median longitudinal section of micropyle, collar, and apex of nucellus, showing these parts in 
greater detail than in fig. 1 4. m., micropyle occupied by the nucellar beak, 5.; co., collar ; 
x, x, the symmetrically placed regions on either side at which the preservation of the collar 
ceases ; p.c., upper part of pollen-chamber ; a., apex of residue of nucellus after detachment 
` of funnel-like beak ; e.ż., epithelioid lining sclerotesta. x80. S 6a. (See p. 371.) 
Pollen-grain cut in transverse section, showing internal walls (a-e) meeting at the centre of the 
section. ez., exospore running obliquely towards the pole of the grain. The same pollen- 
grain is represented in fig. 16, p^ x 180. S74. (See p. 376.) 
The same section drawn from a deeper optical plane. Lettering as in fig. 30. 
PLATE 44. 
Figs. 32,33, and 34. Three views of one pollen-grain cut in almost longitudinal section, Figs. 32 and 34 
represent the two surfaces of the section, fig. 33 an optical section midway between them. 
The cells of the grain have come apart at the centre, leaving a space (fig. 33, c) in which 
the remains of the axis of union of the membranes is obscurely seen (2). w., perforations 
in the walls of the internal cells. The pollen-grain here illustrated is marked p. in fig. 6. 
x 250. S84. (See p. 377.) 
Fig. 35. Pollen-grain marked p." in Pl. 42. figs. 14 & 16. ex., exospore ; c., internal cells; c.b., central 
body or remains of joined internal angles of the cells, at A still continuous with a radial wall. 
d indicates approximate plane of transv. section represented in fig. 16, p.", and figs. 30 & 31; 
e, f, approx. plane of section of pollen-grain, p., fig. 14. x 235. S 74. (Bee 
p. 377.) 
