76 THE STORY OF THE PLANTS. 



union of two cells often produces a fresher, 

 stronger, and more vigorous young one than can 

 be produced by mere division of a single cell. 

 In some way or other, when a plant or animal 

 reaches maturity, and arrives at the limit of its 

 own growth, it produces stronger and livelier 

 young by so combining with another of its own 

 species. 



In the thread-like pond-weeds the two uniting 

 cells are practically similar. They are not dis- 

 tinguished as male and female. Neither of them 

 is larger or smaller than the other; neither of 

 them is more active or more' vigorous than its 

 consort. But in the higher plants a marked dif- 

 ference invariably exists between the two cells 

 that join to form the new individual — a difference 

 of kind ; we have sex now appearing. One of 

 the cells is smaller, and more active; it is called 

 a male cell or pollen-cell. The other is larger, 

 richer, and more passive; it is called d. fe7nale cell, 

 or ovule — that is to say in plain English, a little 

 ^gg. Now the nature of the ovule is such that it 

 cannot grow out into a seed or young plant till it 

 has been united with and fertilised by the smaller 

 but more active and lively pollen-cell. 



Separate organs in the higher plants always 

 produce the pollen-grain and the ovule. These 

 organs are known as stamens and pistils (Fig. 

 15). They are really separate individuals, or 

 males and females. The stamen is the father of 

 the seed, so to speak, and the pistil its mother. 



This is a hard saying, I know, and, in order 

 that you may understand it, I must begin by tell- 

 ing you another point about the plant which I 

 have hitherto to some extent studiously con- 

 cealed from you. It is this — each higher plant is 



