ORGANS OF BEPRODUCTION. 393 



ifig. 839, a), attached to delicate jointed filaments arising from 

 the inner surface of the conceptacle (Jig. 837). The antheridia 

 may either occur in the same conceptacles with the sporangia, 

 or in different ones, and then either on the same, or on distinct 

 individuals. When conceptacles of both kinds occur on the same 

 plant, this is termed monoecious, if on different plants, they are 

 dioecious. By some algologists, the plants are termed hermaphro- 

 dite when both antheridia and sporangia occur in the same 

 conceptacle. The delicate jointed filaments which in all cases 

 surround the sporangia, but upon which no antheridia are found, 

 are termed paraphyses (Jig. 839, p). The antheridium contains 

 a number of spermatozoids, anlherozoids, or phytozoa, of various 

 shapes, each of which is furnished with two cilias of unequal 

 length (Jig. 838). Thuret has clearly proved the existence of 

 sexes in this family of the Algce. 



