RUBE 
mary filaments is built up of hypha-like filaments fusing together into a dense tissue. 
In a later stage the cortex shows a pronounced differentiation, as shown by WILLE 
(1887, p. 72), the innermost layer surroun- 
ding the axial cell-row becoming a conduct- 
ing tissue, the intermediate layer a tissue 
serving for storage, and the outermost, small- 
celled layer having an assimilatory function. 
The cells of the central axis gradually in- 
crease considerably in size and the pits con- 
necting them increase too. The border of the 
two callus plates which cover the thin 
pit-membrane is sometimes bent back and 
continues their way on the surface of the 
thick transverse membrane, a phenomenon 
which is perhaps connected with the peri- 
pheral growth of the pit (Fig. 286, above). 
In older shoots the surface of the cortex is 
often covered by a felt of adventitious shoots 
of unbranched cell-rows issuing from the 
superficial cells (Fig. 286). CRAMER (1864 p. 10 
and pp. 109—110) has mentioned them and 
Fig. 286. P even established three forms of the species 
Plumaria elegans. Longitudinal section of older stem, according to their frequency: at, subglabra; 
perpendicular to the plane of ramification. p, pit . 
seen from the face. 200 : 1. ß; pilosa and Y> tomentosa. 
The sexual organs have never been met 
with at the Danish coasts. The antheridia according to BurrHam form “yellowish 
bunches near the extremities of the pinnules’”’' (1891, p. 247 Pl. XVI figs. 6—7). 
The structure of the procarps has been described by 
PHırLırs (1897 p. 362). The ripe cystocarps are usually 
said to be naked or provided with involucral branches. 
But as the sori of paraspores have really often been 
confounded with cystocarps it may be supposed that the 
latter are always provided with involucral branches. Burr- 
HAM asserts, too, that he has never seen the true cysto- 
carps naked (1893 p. 303). 
Tetrasporangia have only been met with once and 
5 r Fig. 287. 
extremely sparsely. In a paraspore-bearing specimen from  pymaria elegans. Tetrasporangia 
Busserev gathered in July 1918 I found a ripe and an un- before and after division. 390: 1. 
ripe tetrasporangium (Fig. 287). They had a dense, dark- 
red content and a thick, two-layered membrane. Within the thin firm cuticle two 
7 The organs which BurrHan in a foregoing paper (1884, p. 342, Plate XII Fig. 1) took for an- 
theridia are of dubious nature, possibly foreign sporelings. 
