30 ELEMENTARY STUDIES IN BOTANY 



21. Summary. Algae represent the beginnings of the 

 plant kingdom, and all their structures are related to water 

 as a medium. 



The simplest body is a single cell, but among Algae the 

 body advances from the single cell, through cell-colonies, 

 to the many-celled individual, whose form is prevailingly 

 filamentous, although other forms occur. Among the higher 

 Algae, the many-celled body often becomes differentiated 

 into different regions, notably among the marine Algae. 



The simplest form of reproduction is vegetative multipli- 

 cation. In addition to this, Algae developed reproduction 

 by means of spores, which in most cases are swimming cells. 

 Among the Algae there appears also sexual reproduction, at 

 first the gametes seeming to be alike, then differentiating 

 into sperms and eggs. The two kinds of gametes at first 

 are produced by ordinary vegetative cells, but later special 

 cells produce them, which are therefore sex-organs. 



