130 THE OAK 



fertilisation, and the fertilised egg-cell is now termed 

 the oospore, and at once begins to grow into the 

 embryo. 



It would be very interesting to describe at length 

 all the remarkable details of these processes, and their 

 morphological meaning in the light of modern biology, but 

 the limits and purpose of this little book will not admit 

 of that, and I must content myself with this brief resume. 



During this process of fertilisation the cupule has 

 grown up like a scaly wall round the ovary (fig. 34), and 

 the tip of the latter is seen peeping out from its orifice. 



We are now in a position to understand generally 

 the changes that convert the female flower into the 

 cupped acorn. The fertilised oospore becomes the em- 

 bryo (fig. 35, x); it grows at the expense of the contents 

 of the embryo-sac, and develops a radicle, a plumule, 

 and two relatively large cotyledons, which soon become 

 so big that they occupy the whole space in the sac (fig. 

 36). Moreover, the embryo-sac increases to make more 

 room for this growing embryo. And now comes in a 

 curious point. We saw that the ovary consisted of three 

 chambers, each containing two ovules ; each of these 

 six ovules also had its embryo-sac, containing an egg- 

 cell, &c., and each of the total of six egg-cells may be 

 fertilised by the contents of so many pollen-tubes 

 coming from pollen grains on the stigmas. But the 

 rule is that five of the ovules with their contents 

 perish at an early period, because one strong one takes 

 the lead in development, and starves the rest by taking 



