INTRODUCTION TO CRYPTOGAMIC BOTANY. 



209 



Fig. 52. 



a. Cuthria midtifida, fruit with 8 cells, producing large zoospores. 



b. Fruit with 32 cells, producing spermatozoids. 



c. Zoospore. 



d. Spermatozoid. 



e. Oosporangium of SHlophora rhizodes. 



f. Trichosporangium of ditto. 



ff. Small zoospore from Oosporangium. 



h. Larger zoospore from Trichosporangium. 



All magnified, after Thuret. 



193. The divisions into which this great class naturally 

 breaks up are the following : Ectocarpew, Chordarice, Dictyo- 

 tece, LaminaricB, Sporochnacece, and Fucacece, of which a 

 tabular view is subjoined. 



Sctocarpea.—Filiiorm. Spores or cysts external. 

 C%orc?an(8.— Cylindrical, threads interlaced. Cysts im- 

 mersed. 



BiotyotecB.— Scores or cysts superficial, collected in little 



definite patches (sort). 

 Laminarice.—STporea or cysts dispersed in indefinite 



patches, or covering the whole surface. 

 Sporochnacece.— Cysta attached to external threads, which 



are free or conglobated. 

 i^Vcaceffi.— Spores on the walls of globose cavities or con- 



ceptacles. 



