192 
PHARMACEUTICAL BOTANY 
there arises a many noded (jointed) stem which bears whorls of 
slender green leaves at its nodes. Branches are also found issuing 
from some of the nodes which duplicate in appearance the main 
stem. Reproduction is either asexual or sexual. Asexual repro- 
duction is accomplished by means of tuber-like bodies borne on 
submerged parts or by special branches which form rhizoids on their 
lower nodes and later become separated from the parent plant. 
Sexual reproduction is effected through the formation of oogonia 
(female sex organs) and antheridia (male sex organs). These in 
some species are borne on the same plant; in others, on different 
plants. In all cases the sexual organs are produced at the nodes. 
The oogonium develops within itself a large ovum or egg. The 
antheridium produces within its wall numerous motile sperms. 
Upon the maturation of the antheridium the sperms are liberated 
into the water, and, propelled by their cilia, find their way to the 
oogonia which they enter, the one best adapted fusing with the egg 
in each case and fertilizing it. The resultant cell is called the 
oospore. This undergoes a resting stage and later germinates as a 
proembryo. The proembryo consists of a simple filament and a 
long rhizoidal cell. From this proembryo, the adult stem arises as a 
side branch. 
Class II. — Phaeophyce^e, tiie Brown Alg^: 
Mostly marine forms showing great diversity in the form of their 
vegetative bodies. They occur for the most part in salt water be- 
tween the high and low tide marks. Their bodies are usually fixed 
to some support in the water by means of a holdfast, and are often 
highly differentiated both as to form and tissues. Some reach 
hundreds of feet in length as, for example, Macrocyslis which grows 
in the Pacific Ocean off the coast of California. They all contain 
the brown pigment called phycophcein and the green pigment, chloro- 
phyll both of which are present in their chromatophores. A yel- 
lowish pigment called phycoxanthin has also been isolated from some 
of the species. Many of the kelps and rockweeds belonging to this 
class have long been sources of iodine, potash and sodium. 
A Filamentous Brown Alga, Ectocarpus Siliculosus. — Ecto- 
corpus occurs as tufts of branching filaments, each of which 
