CHAPTER III. 



Subdivision II.— THALLOPHYTA. 

 Class I. — Alg^e {Seaweeds). 



Protophyta — Primordial Types of Plant Life — Transition from Uni- 

 cellular through Cell Colonies to Multicellular Plants — 

 Earliest Indications of Sexual Reproduction — Terminal Groups of 

 Protophytes — AlgEe Proper— Gradual Differentiation of Vegetative 

 and Reproductive Parts — Evolution of nevi' Groups — Distribution 

 — Fossil Algae. 



(A) Protophyta. 



The Protophyta, as the name denotes, includes the primordial 

 types of plant life, and are often considered as belonging to 

 the Algae, but are treated by Bennett as a distinct sub- 

 division. This author states, however, that "whether the 

 Protophyta should be reckoned as a distinct subdivision 

 from the Algae, or only as the lowest members of that 

 great series, is a question rather of convenience than of 

 principle." The great bulk of forms included in the present 

 class are unicellular, without a distinct process of sexual 

 reproduction, and are either destitute of chlorophyll, or this 

 substance may be present in a pure form, or its characteristic 

 green colour masked by the additional presence of blue or 

 brown colouring matter. Although the above characters 



