Natural History 629 



crimson filaments. In the willow the two kinds of flower grow 

 on separate bushes. 



The Secret of the Seed 



Before the ovule can develop into a seed, the egg-cell it 

 contains must be fertilised by the pollen. The pollen is received 

 on the stigma, a moist receptive surface, sometimes borne on a 

 long style, as in the sage, sometimes sessile on the ovary, as in 

 the tulip. The pollen-grain germinates and sends a fine tube 

 down through the tissues of the style and ovary to the ovule. 

 The process of fertilisation is preceded by a long process of intri- 

 cate preparation. In the ovule there has been formed a single 

 large cell the embryo-sac containing a number of cells, of 

 which two are important; of these one is the egg-cell or female 

 reproductive body. 



The germinating pollen-grain contains three nuclei, one of 

 which is the male reproductive body or sperm. When the pollen- 

 tube reaches the ovule it brings its contents to the embryo-sac, and 

 the sperm and the egg-cell fuse together. In each of these there 

 is packed away the inheritance of one parent; the result of the 

 fusion, the fertilised egg-cell, contains all the factors which, as 

 development proceeds, will stamp the new organism with the 

 features of its kind. The egg-cell, stimulated by fertilisation, 

 commences to divide and grows into an embryo with a root, two 

 leaves, and a shoot bud ; these parts can be easily seen if we open 

 up a soaked pea or bean. Development goes so far and then 

 stops; the young tissues dry up as the seed ripens; it is cast loose 

 in a state of rest. The higher plants, like the highest animals, 

 liberate young ones; they are truly viviparous. 



Why Flowers are Bright 



In the flower, tihen, we recognise the ovary as the organ 

 which contains the female reproductive bodies, in which the seed 

 is matured ; the stamens produce the fertilising pollen ; the calyx 



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