BROWN AND RED ALG&. 



117 



phyceae (floridese). In gracillaria these fruit bodies occur scattered over 

 the thallus. They are somewhat flask-shaped, are partly sunk in the 



Fig. 122. Fig. 123. Fig. 124. 



Antheridia of fucus, on Antheridia of fucus with Egg of fucus surrounded 

 branched threads. escaping spermatozoids. by spermatozoids. 



thallus, and the conical end projects strongly above the surface. The car- 

 pospores are grouped in radiating threads within the oval c- vity of the 



Fig. 125. 



Fertilization in fucus ; fn, female nucleus ; mn, male nucleus; n, nucleolus. In the left 

 figure the male nucleus is shown moving down through the cytoplasm of the egg ; in the 

 remaining figures the cytoplasm of the egg is omitted. (After Strasburger.) 



cystocarp. These cystocarps are developed as a result of fertilization. 

 Other plants bear gonidia in groups of four, the so-called tetraspores. 



272. Rhabdonia. This plant is about the same size as the gracillaria, 

 though it possesses more filiform branches. The cystocarps form prominent 

 elevations, while the carpospores lie in separated groups around the periph- 

 ery of a sterile tissue within the cavity. (See figs. 128, 129.) Gonidia in 

 the form of tetraspores are also developed in rhabdonia. 



