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BOTANY: PRINCIPLES AND PROBLEMS 



water outside. The oospore settles to the bottom, attaches 

 itself, and develops directly into a new plant. 



Rhodophyceae or Red Algae. — These are a very varied 

 group, rich in species, almost exclusively marine, and reaching 

 their best development in the warmer seas. Most of them grow 

 entirely submersed, below tide marks, and are therefore not 



Fig. 160. — Nemalion. A, procarp at end of a filament, c, carpogonium and 

 t, trichogyne, to which several sperms are attached. A male nucleus has entered 

 the carpogonium. B, cystocarp, which has arisen from the fertilized carpogon- 

 ium. Carpospores are developing at the ends of short filaments. C, antheridia, 

 groups of small cells each of which produces a sperm. X 60. 



particularly conspicuous or familiar. The vegetative body tends 

 to be delicate, filamentous, and much-branched, in contrast to 

 the bulky thallus of the brown algae. The Rhodophyceae are 

 distinguished from all other algae by their characteristic reddish 

 color (due to the pigment phycoerythrin which is present with 

 chlorophyll); by the complete absence of motile cells of any kind, 

 and by a highly specialized type of sexual reproduction. They 

 do not include primitive types but seem to have arisen from a 



