6l2 
Pearson . — On the Micro sporangium and Microspore of 
c. 
— It 
no such explanation is possible, for although the ground tissue contains 
a great development of sclerenchyma, its elements are for the most part 
isolated and its distribution is quite independent of the arrangement of the 
bundles (Text-fig. 4). It is stated that one of the outstanding differences 
between Calamostachys and Palaeostachya is the absence of any considerable 
reflection of the sporangiophore trace in the former. Hickling’s conclusion 
that the two forms need not be remotely separated on this account receives 
some support from the fact that we have in Gnetum an even greater difference 
of a like character between living species of the same genus. 
From the nodes of the network formed by the branching and ana- 
stomosis of the traces described above, short branches arise and proceed 
directly outwards towards the insertions of the flowers. These are more 
or less concentric or distinctly collateral ; in the latter case the phloem may 
be situated on either the upper or the lower side of the xylem. 1 Each of 
these upon entering the floral axis 
gives off two branches in a vertical 
plane which pass, the one into the 
upper, the other into the lower, 
perianth leaf of the male flower 
(Text-fig. 3) ; the main trunk almost 
immediately forks in a horizontal 
plane and becomes resolved into 
two xylem-traces (PI. LX, Fig. 3), 
which pass up the axis of the flower 
and end blindly, one beneath each 
anther, as described by Strasburger. 
In still another character of the male spike, the African species differ 
from G. scandens and from other Indo-Malayan species whose structure has 
been investigated. In G. scandens the bundles of the leaf-cupule lie not 
far beneath the upper epidermis, with which they are united by continuous 
tissue. In both the African species a large mucilage canal intervenes 
between the leaf-bundle and the upper epidermis 2 (cf. Text-figs. 3 and 4; 
PI. LX, Fig. 2). This canal is continuous all round the cupule. The early 
stages of its development have not been seen, but it is clearly lysigenous 
in origin. Its roof usually consists merely of the epidermal cells, to which, 
however, the remains of underlying tissue are frequently attached. Its occur- 
rence is not limited to the flower-bearing nodes, for it attains complete 
development in the youngest node, which bears no flowers (Text-fig. 6). 
In the African species also the pith tissue of the older internodes of the 
inflorescence is always disorganized and its cavity filled with a mass of 
mucilage. In herbarium specimens the internodes are shrunk to such an 
extent that they have the form of stout threads connecting the nodes, which 
1 Cf. Thoday (’ll), p. 1106. 2 1 . c., p. 1104. 
Text-fig. 5. Longitudinal section through apex 
of inflorescence of G. scandens. x 15. 
