22 BOTANY. [CHAP. i. 



fibro-vascular bundles, was the evolution of the structure 

 popularly known as the flower. The only mode of plant 

 reproduction hitherto mentioned fission or cell-division 

 is termed the asexual or vegetative mode, but even in 

 the Algae a second and much more highly evolved method 

 is known called the sexual mode of reproduction, which 

 fundamentally consists in the amalgamation of the proto- 

 plasm of two distinct bodies, presumably male and 

 female, to form a single reproductive organ called an 

 oospore } but which would popularly be called a seed. Now 

 in all seaweeds the male or fertilizing element consists of 

 a very minute portion of protoplasm that becomes free 

 from the plant, and possesses the peculiarity of exhibiting 

 spontaneous movement, swimming about in the water 

 by means of very fine hair-like appendages or cilia. The 

 object of this animal-like movement of the fertilizing 

 body or antherozoid is to enable it to come in contact 

 with the female element with which its substance blends 

 the act of fertilization and a minute body results 

 that eventually becomes liberated from the parent plant, 

 and under favourable conditions germinates or sprouts 

 and produces in turn a plant resembling the one to which 

 it owed its origin. This mode of sexual reproduction by 

 means of motile antherozoids that reached the female by 

 swimming in water is still kept up by several groups 

 of plants that had firmly established themselves on dry 

 land, as the Liverworts (Hepaticce), Mosses (Musci), 

 Ferns (Filices], and Club-mosses (Lycopodiacece) , conse- 

 quently in all the above groups there is as a rule a 

 tendency to grow in damp districts, and the sexual mode 

 of reproduction takes place during the winter in tem- 

 perate regions, or during the rainy season in the tropics, 



