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PHARMACEUTICAL BOTANY 
SUBDIVISION III. — ALG/E 
Low forms of thallophytes of terrestrial and aquatic distribution 
consisting for the most part of single cells or rows of single cells 
joined end to end to form filaments. The higher forms, however, 
possess structures, which might be compared to stems and leaves of 
higher plants although more rudimentary in structure. They 
contain chlorophyll or some other pigment, and so can use the CO2 
and H 2 0 in the same manner as higher plants, e.g., in assimilating 
and providing for their own nutrition. Archegonia are absent in 
this group. 
Class I. — Chlorophyce^e, the Green Alg,e 
A large assemblage of terrestrial or aquatic plants many of which 
are vastly different from one another. In this group the cells are 
observed to possess distinct nuclei and chromatophores, the latter 
containing a green oil-like pigment called chlorophyll. Reproduc- 
tion is mostly by ciliated cells called zoospores but in some forms is 
accomplished by the fertilization of egg-cells and in others by simple 
division. 
1. Order Protococcales or One-celled Green Algae. — This order 
contains nearly all of the one-celled green algae excepting the 
diatoms and desmids. 
Family Pleurococcaceae. — Pleurococcus vulgaris is a one-celled 
green alga, millions of which, living together in colonial fashion, con- 
stitute the so-called “green stain” that is common on the north 
sides of tree trunks, stone walls and fences. Each organism con- 
sists of a protoplast surrounded by a cell wall of cellulose. The 
protoplast contains a chromatophore, cytoplasm and nucleus. 
Reproduction takes place by the protoplast dividing into two equal 
parts and laying down a cell wall forming two daughter-protoplasts. 
These may again divide to form four granddaughter-protoplasts. 
Still another division may occur as a result of which eight great- 
granddaughter-protoplasts are formed which frequently adhere to 
one another forming colonies. 
2. Order Confervales. — In this order are included a variety of 
green filamentous and membranous forms some of which show sexual 
reproduction. 
