969 
the Inflorescences and Flowers of Ephedra. 
of the ovule, and consequently the free part of the inner integument gets 
carried further up ; in Text-fig. XIII. 3 its level of freedom is about half-way 
up the ovule, but in the ripe seed it is about two-thirds of the way up 
(Text-fig. XI. i). 1 Even in the mature seed, however, the free apex of the 
nucellus is conspicuous and fairly massive. 
It is interesting to compare the relative development of the different 
regions of the ovule in the three genera of the Gnetales. In Gnetum the 
method of development is similar to that in Ephedra in that the apical 
region of the ovule develops first, but in the later stages this region appears 
practically to cease to grow, and it is almost entirely to the great growth of 
3 
Text-fig. xnr. 1-3. Three stages in the growth of the ovule in Ephedra, i. Early stage with 
two integuments arising together at the base of the ovule. 2. Young ovule in which the apex has 
grown considerably, but the two integuments still originate close together. 3. Fertilization stage in 
which the region between the integuments has begun to enlarge. 
the intermediate region, as in the Cycads, that the enlargement of the ovule 
is due. The apex of the nucellus after fertilization becomes hardened and 
withered, as it does also later and to a much smaller extent in Ephedra. 
In W ehvitschia we unfortunately know little of the earlier stages. In 
Text-fig. VIII, p. 196 of an earlier paper, 2 a stage is drawn in which the integu- 
ments are fairly close together. Here also the early growth in the apical 
region is followed by the enlargement of the intermediate region, but it also 
appears that here further great expansion of the apical region takes place, 
producing a massive nucellar apex far larger in size than that in Ephedra , 
though more like Ephedra than Gnetum . It has already been suggested 3 
that the Angiosperms illustrate the further development of this tendency. 
1 Or even three-quarters, Strasburger, 1872, Fig. 50, PI. XVI. 
2 Sykes, 1910. 3 Sykes, 1910, pp. 218-19. 
