70 THE PLANT OVUM less, vi 



section of an ovule shows it to contain a large cavity, the 

 embryo-sac or megaspore (see Fig. 126, d), at one end of 

 which is a microscopic cell {oii, and Fig. 1 1 b), consisting as 

 usual of protoplasm (plsm), nucleus {nu). and nucleolus 

 (««'). This is the ovum or egg-cell of the plant : from it 

 the new plant, which springs from the germinating seed, 

 arises. Thus the higher plants, like the higher animals, 

 are, in their earliest stages of existence, microscopic and 

 unicellular. 



