



1917] DUNN—DUMONTIA 435 



carpospores persist through the winter. These holdfasts, in the 

 following June, produce adventitious shoots which develop into 

 tetrasporic plants. Lewis believes that this is in general the 



many 



also exceptions to the separation in point of time of the two 

 generations. This separation is never of a perfectly sharp and 

 definite character, as the generations always overlap to a certain 



midsummer 



May and J 



t South Harpswell is evidently 

 mentioned. The carpospores 



Tune and July. This 



from the fact that the carpospores 

 escaDiner from the cvstocarn. also t 



plants 3-7 cm. in height were often found growing beside the stumps 

 of the frayed off cystocarpic plants. Germination of the tetraspores 

 has not been seen, but the occurrence of only male and female 



in 



through the winter in the form of sporelings derived from the 

 tetraspores discharged in June and July. 



VEGETATIVE STRUCTURE 



The holdfast of Dumontia is a platelike body composed of a single 



filaments 



ing, vertical branch (figs. 8, 9) . These vertical branches are closely 

 packed together, averaging about 12 cells in length, and are very 

 regular in form and arrangement. They are generally dichoto- 

 mously branched. The cells of the horizontal filaments usually 



form no descending 



branches. The few branches of this character 

 observed consisted of only one cell (fig. 8). It is evident from the 



arrangement 



they develop by apical growth. 



form 



the upright portion of this alga (fig. 9). In such longitudinal fila- 

 ments there is a gradual increase in the length of the cells. They 

 are closely packed together at the base of the main axis, forming 

 a solid tissue (fig. 9). At about o . 1 



mm 



