965 
the Inflorescences and Flowers of Ephedra. 
the tip of the tube and which is continuous downwards as a thick muci- 
laginous lining to the tube. The chink between the micropylar tube and 
the integument is also closed by the papillae of the outer integument, and 
Text-fig. ix. Longitudinal section of ovule of E. distachya , older than the one drawn in 
Text-fig. vni. The fibres internal to the vascular bundles are seen to be strongly lignified. 
in this manner the developing embryo would appear to be as effectively 
protected as in Gnetum 1 with its special apparatus. 
The ring of vascular bundles which 
enters the base of the ovule does not 
run up as far as the free region of the 
inner integument, but terminates quite 
low down in a mass of transfusion 
tracheides. One of the most charac- 
teristic features of the Ephedra ovule is 
the sharp demarcation of the large 
empty cells of the nucellar tissue from 
the smaller celled tissue which forms 
the free part of the inner integument 
and is also prolonged downwards right 
round the base of the nucellus (Text- 
fig. XI. 2). The ring of vascular tissue 
is situated in the integumental region. 
This differentiation is not of course pre- 
sent in the earliest stages, its cause being text-fig. x. Transverse section of 
the proximity and growth of the pro- nucellus and inner integument just above the 
, . . . 1 level at which the integument becomes free, 
thallus, in consequence ot which the I = inner integument ; N = nucellus ; Pr = 
cells of the nucellus become flattened pwthallus ; l = layer of papillate cells on 
periphery 01 nucellus. 
and empty. Still the differentiation is of 
some interest, nothing of the kind having been seen in Gnetum or Welwitschia. 
1 Berridge, 1911; Thoday (Sykes), 1911. 
