246 PHARMACEUTICAL BOTANY 



gains an entrance, after which its nucleus fuses with that of the egg 

 to form an oospore. The oospore at once develops into a new Fucus 

 plant. 



CLASS III. RHODOPHYCE^E, THE RED 



A greatly diversified group comprising the majority of marine algae 

 but represented also by some fresh-water forms. The marine red 

 algae are generally found at or just beyond the low water mark. 

 Their vegetative bodies vary from simple branching filaments 

 through all gradations to forms differentiated into branching stems, 

 holdfasts and leaves. It has been observed that many of the higher 

 types are composed of numerous filaments which are arranged so 

 closely and connected so intimately by protoplasmic processes 

 as to resemble the tissues of plants higher up. Their color may be 

 red, purple, violet, or reddish-brown or even green and is due to the 

 presence of phycoerythrin, a red pigment, which is found in the 

 chromatophores with but frequently masking the chlorophyll. 



Chondrus crispus and Gigartina mamillosa yield the official drug 

 Cbondrus, Irish Moss or Carragheen. Both are purplish-red in 

 color. Each consists of a dichotomously branched thallus the 

 lower portion of which is differentiated as a stipe or stalk; the basal 

 portion of which, called the holdfast, clings to the rock. The upper 

 part is several times forked and its terminal segments appear notched 

 or bilobed. Scattered here and there over the segments of the 

 thallus will be noted sporangia which, when mature, contain tetra- 

 s pores. In Chondrus crispus the sporangia are elliptical and em- 

 bedded in the thallus near its surface, whereas in Gigartina they are 

 ovate and project outward from the surface of the segments. Upon 

 the ripening of these structures the spores are discharged into the 

 sea water. These sooner or later germinate into new Chondrus or 

 Gogartina organisms. 



The dried mucilaginous substance extracted -from Gracilaria 

 lichenoides, Gelidium and Gloiopeltis and other species of red algae 

 growing in the sea along the eastern coast of Asia constitutes the 

 drug Agar, a most valuable ingredient in culture media as well as 

 a laxative. 



