178 



SEAWEEDS 



flora of the warm and temperate Atlantic and Medi- 

 terranean. Characium, a genus of about thirty spe- 

 cies, of which only two are marine, is a stalked form 

 with ovate cells, and Codiolum and SyTddion more or 

 less resemble it vegetatively. 



The Reproductive Organs. Chlorochytrium pos- 

 sesses gametes which escape from the mother-cell 

 embedded in a mucilaginous mass, and conjugate 



FIG. 55. Halngphrrra viridis. a, showing the protoplasm gatlierecl round 

 the nuclei and lining the wall ; 6, the outer membrane, cast ott' after enlarge- 

 ment of the sphere, the daughter-cells separated from the wall ; c, d, e, stages 

 in the development of zoospores ; at e, the hour-glass shape is preliminary 

 to division into two ; /, zoospore highly magnified. (After Schmitz). 



before leaving it. The zygote remains motile by 

 means of the four cilia (of the two bi-ciliated 

 gametes), and eventually on coming to rest 

 surrounds itself with a membrane, and pene- 

 trates the tissue of the host-plant by means of 

 a short germ-tube. C. dcrmatocolax, which inhabits 

 Polysiphonia and Sphacclaria, and C. inclusum, which 



