1917 Hurd; on Algae in Winter 315 



Lewis (1912) reports that at Woods Hole Polysiphonia violacea, 

 Dasya and Griffithsia sporelings grew very little after August 15, and by 

 September 1 were disintegrating. In a later paper he says that Polysi- 

 phonia violacea plants which have attained any considerable size, die at 

 the approach of cold weather while the young tetrasporic sporelings are 

 dormant during the winter. Thus at Woods Hole Polysiphonia is present 

 in winter only as young tetrasporic sporelings, the plants found in early 

 summer are tetrasporic and those of the late summer are sexual. Lewis 

 found only one plant out of ten to be sexual in .July, while in August 

 the majority were sexual. 



Observations at Lincoln Beach show that this seasonal life cycle does 

 not hold for the Puget Sound species, since large healthy plants were 

 abundant all winter. Some of these were sexual and some tetrasporic. 

 Nearly all of the cystocarps found in winter were very young, many 

 with the trichogyne still attached. In Polysiphonia californica the tetra- 

 sporic plants predominate early in February, but later the number of te- 

 trasporic and carposporic plants is about the same. This is shown by the 

 following data: 



Feb. 12, Lincoln Beach: 12 tetrasporic, carposporic, antheridial, sterile. 



Feb. 24, Lincoln Beach: 35 tetrasporic, 5 carposporic, 3 antheridial, 5 sterile. 



Feb. 28, Fort Lawton: 4 tetrasporic, 8 carposporic, 1 antheridial, 5 sterile. 



Mar. 25, Lincoln Beach: 8 tetrasporic, 9 carposporic, 3 antheridial, 5 sterile. 



Apr. 22, Lincoln Beach: 5 tetrasporic, 4 carposporic, 1 antheridial, 2 sterile. 



Thus until February 24, the number of tetrasporic plants of P. cal- 

 ifornica greatly exceeded the number of carposporic ones ; but by the end 

 of March there were practically the same number of each. This, together 

 with the observation that the cystocarps were all young, suggests that 

 although the life histories of the Puget Sound plants do not follow those 

 of Woods Hole in point of seasonal occurrence, the two generations may 

 be at least partly conditioned by the season. No sexual plants of Polysi- 

 phonia urceolata were found. The majority were sterile, the rest tetra- 

 S))oric. 



Lewis (1914) considers the seasonal life cycle of Polysiphonia char- 

 acteristic of many New England algae, mentioning Agardhiella, Champia, 

 Grinnellia, Chondria and Atlantic species of Polysiphonia. He says that 

 Agardhiella shows the two generations clearly separated in point of time, 

 all the larger individuals being killed at the approach of winter. This 

 is an interesting contrast to conditions in Puget Sound in which large 

 specimens of Agardhiella were found all winter, and both cystocarpic and 

 tetrasporic individuals were found in equal numbers. The same is true of 

 a considerable number of red algae found reproducing here both asexually 

 and sexually all winter (see group 1, page 311-). 



