the neighborhood of the reproductive organs, ..here t}ie pro- 

 cesses of metabolism may be assumed to be most active, and 

 are usually absent on the sterile portions of the plant, 

 it seems likely that they perform the functions of absorp- 

 tion and respiration, as is believed by ROSEUVIITGE ('Oo) to 

 be the functions of similar organs in tlie R}iodomelaceae, 



Rhizoids are frequently formed from the older vegeta- 

 tive cells. Protoplasm accujnulates at a spot on the lov/er 

 half, or near the middle, or even at tiines on the upper 

 half of the cell (fig. ), and pushes out as a hollow tube 

 v/ith a plug of protoplasm at its tip (fig. t8),. in the 

 cytoplasm of a. rhizoid the chromc-^tophores e:re rather few 

 in number, and the nuclei are smaller than usual in vegeta- 

 tive cells. The average diameter of a rhizoid is about 

 80 1^ ; the length 2 irnn or more. The rhizoid secretes a 

 rather thick cellulose wall. The longer rhizoids become 

 divided into two or t}-iree long cylindrical cells by tlie 

 centripetal growth of a cellulose ring such as occurs in 

 the division of certain vegetative cells. 



The rhizoids so formed attaxh themselves tc^ any neigh- 

 boring object^, curving around it in tlie ma.nner of a tendril 

 (fig. 49) . In this v/ay the plant is more securely anchored 

 tlian it v/ould be by a holdfast alone. Further, rhizoids 



