I 84 PLANT LIFE. 



Ulothrix, the nonsexual cells produced for multipli- 

 cation are specialised. They possess two lashes, or 

 cilia, by which they can swim at a considerable speed. 

 They eventually come to rest, and grow into a new 

 Ulothrix. In the Red Algae the nonsexual spores 

 occur in groups of four. They are specialised for 

 colonising, being a darker red, probably full of reserve 

 food material, and they cire larger than the ordinary 

 cells, but they have no swimming cilia. 



The sexual spores are male and female. The male, or 

 spermatozoid, is generally a very minute speck of nuclear 

 matter with long lashes by which it swims actively in 

 the water. The female spore is generally larger, and 

 often contains much food material ; it is not capable of 

 motion as it has no swimming cilia. In these, the 

 lowest types of life, therefore, the male is more active 

 and enterprising than the female, and this difference 

 persists through the whole vegetable and animal king- 

 dom, with apparently very few exceptions. 



The egg-cell resulting from the union of the male 

 and female spores sometimes germinates directly ; but, 

 in many cases — in the Red Algae and in others — the 

 fertilised o.^^ begins to divide, and forms a quantity of 

 spores each of which can grow into a new plant. In 

 the Algae, therefore, there are male, female, and egg-cell 

 spores in addition to the nonsexual forms. Dr. Scott 

 gives an excellent account of Pelvetia and other types 

 to which reference should be made. 



The third division of the water flora consists of certain 

 fringing transitional plants, which make their appearance 

 whenever land vegetation is interrupted by a sheet of 

 water. These plants sometimes cover large areas of 

 mud or sand, or of marshy fenland. In Britain they 

 are essentially transitional forms. 



