THE ALG^E 



207 



cavity, and thus forms a new antheridium inside the 

 membrane of the old one. The spermatia are excessively 

 minute, not more than 200 millimetre in diameter. 



FIG. 89, Callithamnion corymlosum ; part of a male plant 

 bearing the clusters of antheridia (a). Magnified about 150. 

 sp, detached group of antheridia, surrounded by free sperm- 

 atia. Magnified about 240. (After Thuret and Bornet. ) 



