530 
Gibbs . — On the Development of the 
prothallial tissue (PL XLIX, P"ig. 6 , arch.), and are long and tapering, similar 
in shape to those described by Lawson in Sciadopitys verticillata ( 30 , p. 413), 
and in Cephalotaxns Foriunei by Coker ( 17 , p. 5). All the five archegonia 
are in the maturation stage, when according to Blackman ( 4 , p. 404) 
the uniformly reticulated nucleus increases enormously in size and moves 
into the centre of the egg (Fig. 6 a , e.n.) Lawson ( 30 , p. 44) describes the 
same result in Sciadopitys verticillata , where the egg nucleus enlarges 
enormously and moves down to the centre of the cell. The protoplasm 
of the archegonia is much vacuolated, and contains densely staining proteid 
bodies. 
As far as could be ascertained in the scanty material available the 
neck cells (Fig. 6 a , n. c.) consist of two to six cells. Coker ( 15 , p. 98) gives 
them as from two to twenty-five in P. coriacea. Below the archegonia 
there is a central cylinder of small-celled tissue (Fig. 6 , cen. cyl.) which 
Coker has also described for P. coriacea ( 1 . c., p. 96). The cells of the 
prothallus are mostly binucleate. Saxton ( 36 , p. 175) records in Wid- 
dringtonia that this binucleate condition in the prothallus is initiated on the 
maturation of the oosphere. The cells increase in size towards the peri- 
phery, which is limited by an epidermal layer of small uninucleate cells with 
denser staining contents. This modified epidermal layer, which remains 
almost free from starch, is characteristic of all species examined (PI. LI, 
Fig. 39 b). Coker ( 15 , p. 97) has described a similar layer for P. coriacea , 
and suggests that it is modified for secretion and correlated with the absence 
of a spongy layer in that species ; but in all the Podocarpus material exam- 
ined in the present instance, well-marked ‘ spongy tissue’ or tapetum was 
invariably present (PI. LIII, Figs. 74 and 75) in conjunction with the 
differentiated epidermal layer. PI. XLIX, Fig. 6 shows the prothallus con- 
tracted on one side, due to imperfect fixation, the tissue being so very delicate 
before starch formation is well under way. Contraction is also seen between 
the necks of the archegonia, where the tissue often becomes folded by 
pressure and projects, forming a point at the apex of the gametophyte 
(PI. L, P"ig. 37). This contraction, in microtome sections, often gives 
the appearance of the archegonia lying in pits. 
The prothallus is surrounded by a delicate two-layered megaspore 
membrane, of which the fibrous layer turns yellow both with iodine and 
chloro-zinc iodine. The whole membrane can be dissected off the prothallus 
in its entirety. 
In every species examined a megaspore membrane was found to be 
present. This membrane is conspicuous in microtome sections, taking 
a mauve-red colour in gentian violet and Bismarck brown (PI. LIII, Figs. 74 
and 75), and staining red in safranin when dissected off. It resists the 
action of iodine and sulphuric acid, but in every case responded to the iron 
sulphate test for tannin. 
