962 Thoday and Ber ridge . — The Anatomy and Morphology of 
instead of four (Text-fig. VI. 6'- 10'). This case is intermediate between the 
first two cases and Case 4, in which one of the median axillary bundles is 
not formed at all, and only three bundles enter the base of the ovule (Text- 
fig. VI. 6 // -io // ). This is the case described by Strasburger 1 as normal, but 
it here seemed to be exceptional, for it only occurred in one ovule out of 
seven or eight. Case 3 was the most common. 
(d) Relation of E. altissima to E. distachya. 
The series of cases just described seems to indicate that in fairly 
recent times changes must have taken place in E. altissima which have 
resulted in the modification of the biovulate to produce the uniovulate 
condition. There is other evidence which indicates that this change has 
been brought about by the fusion of the two axillary ovules to form one 
apparently terminal one. In some of the biovulate cones each ovule has 
Text-fig. vii. 1-3. Diagrams of three of the numerous uniovulate cones of E. altissima which 
show evidence of derivation from a biovulate condition. In Diagram 1 the abortive ovule is merely 
a mass of undifferentiated tissue with a cavity ; in Diagram 2 the abortive nucellus is fused at the 
apex with the fertile nucellus ; in Diagram 3 the abortive nucellus is much better developed and the 
wall of common integumental tissue which separates it from the fertile nucellus is continued upwards 
above the region of fusion of nucellus and integument, a small free portion being present, p ., 
prothallus; n L , fertile nucellus; n 2 , abortive nucellus ; id. , common portion of inner integument free 
from the nucellus higher up (#) ; o.i., outer integument ; c., cavity representing abortive nucellus. 
both outer and inner integuments, but in many cases a common outer 
integument is present. In one example in which there was a common 
outer integument both ovules were fertile, but usually one is more or less 
abortive. This abortive ovule is often fused to the lower part of the inner 
integument of its fully developed companion, distorting and pressing aside 
its base ; frequently it is merely a mass of undifferentiated tissue with 
a cavity in the middle (Text-fig. VII. 1), having an independent cup of 
suberized tissue at its base like that always found at the base of the fertile 
ovule. Sometimes, however, nucellar tissue 2 occurs within the cavity of the 
abortive ovule. This is the case in the example represented in Fig. io 3 
1 Strasburger, 1872, Fig. 55 a and b, Taf. XVI. 
2 It is remarkably easy in Ephedra to distinguish the nucellar tissue from the surrounding layers 
of the inner integument, even in the common basal region ; pp. 9 66, 967, Text -fig. XI. 2. 
