55 ^ 
Gibbs . — On the Development of the 
distribution (on the phloem or ventral side of the bundles) suggests that they 
play an important part in the very active metabolism of the ovuliferous 
scale, which controls the developing ovule. The complete organization of 
the former in the pre-fertilization stage, when even the lignification processes 
in the tissue of the same and of the integument have begun, also the meta- 
morphosis of the bract bases, show how vital these rapid metabolic processes 
must be, as their action is so limited in period. 
With the growth of the embryo the activity of the zone of tannin cells 
at the base of the integument and nucellus seems to cease, as in the first 
case the walls of the cells lignify, and in the second the entire tissue is 
digested by the rapidly growing ? gametophyte. The prothalius is about 
two-thirds its mature size at fertilization, and independently elaborates its 
own starch supplies for the nutrition of the embryo, merely drawing on the 
sporophyte for crude materials. The conveyance of supplies must be limited, 
once the nucellar tapetum no longer functions, to the phloem strands, which, 
as we have seen, penetrate the lignifying tissues (PI. LIII, Fig. 72) in greater 
or less degree, through specialized areas. This secondary induration is 
different in form from that which obtains from about the pollination stage in 
the hypodermal cells at the apex of the integument. These cells are 
spirally thickened, the walls being very thick (PL LI, Fig. 57 a), and limited 
to a very small area. 
The cells of the integument, on the contrary, show ordinary lignification 
of the walls with centripetal development, as seen in P. Totara , where in 
a young state only the peripheral layers were lignified, which had increased 
to half the tissue in the pre-fertilization stage, and it is evidently initiated in 
the zone of the nutrient tannin and starch cells as their available supplies are 
absorbed and their activity ceases. 
In Fig. 62 a longitudinal section of the strobilus of this species shows 
three bracts, one of the upper pair fertile, and a lower sterile one, the presence 
of which was quite unnoticeableon examinationbefore selection for embedding, 
and only revealed in the microtome series. Attention may also be called to 
the fact that, were the third bract placed decussately to the upper pair, the 
apex would not come into the radial section figured (Fig. 62, br. 3), but only 
the vascular strand seen, as figured in P. Totara (Fig. 58, tra. of 3 v.b.). 
The tissue of the integument is entirely indurated and lignified, turning 
yellow with potash and red in phloroglucin. The nucellar tissue is crushed 
and empty (Fig. 62, nuc). 
The megaspore membrane can still be traced, limiting the ? pro- 
thallus — indeed it peels off on disarrangement of the tissues ; the prothalius 
cells are packed with starch, with an embryo about half the length of the 
prothalius in the centre, of which the exact stage could not be distinguished, 
the tissue having to a certain extent dried up. 
