FUCALES (HETEROGENERATAE) 189 



REFERENCES 



Desmarestia. Abe, K. (1938). Sci. Rep. Tohoku Univ. ivth ser. 12, 475. 



Eisenia. Hollenberg, G. J. (1939). Amer. J. Bot. 26, 2^. 



Laminaria. Kanda, T. (1936). Sci. Pap. Inst. Alg. Res. Hokkaido Univ. 



1, 221. 



Laminaria. Kylin, H. (19 16). Svensk hot. Tidskr. 10, 551. 



Chorda. Kylin, H. (191 8). Svensk hot. Tidskr. 12, i. 



Laminaria. Schreiber, E. (1930). Planta, 12, 331. 



Desmarestia. Schreiber, E. (1932). Z. Bot. 25, 561. 



Saccorhiza. Setchell, W. A. (1891). Proc. Amer. Acad. Sci. 26, 177. 



Eisenia. Setchell, W. A. (1896). Erythrea, 4, 155. 



Embryology, Regeneration. Setchell, W. A. (1905). Univ. Cal. Publ. Bot. 



2, 115- 



General. Williams, J. Lloyd (1925). Rep. Brit. Ass. Pres. Address, 

 Sect. K, p. 182. 



*CYCLOSPOREAE— 

 FUCALES (HETEROGENERATAE) 



The sporophytic plants are even more dominant in the life cycle 

 than in the Laminariales, but although diploid there is no apparent 

 asexual reproduction, the plants always reproducing by means of 

 ova and antherozoids. There is considerable tissue differentiation, 

 and in their external features the plants exhibit much more variation 

 than is to be found in the Laminariales. Some workers consider 

 that the structures called oogonia and antheridia are really macro- 

 and microsporangia producing mega- and microspores which 

 germinate before they are liberated from the sporangium, so that 

 while the reproductive bodies have their origin as spores, neverthe- 

 less the liberated products are gametes. This view is held by the 

 present author and is discussed more fully later (cf. p. 258). In the 

 primitive condition eight ova are produced in each oogonium and 

 sixty-four antherozoids in each antheridium. Meiosis takes place 

 during the first two divisions in the formation of microspores, and 

 as there is often a pause after the second division the first four 

 nuclei have been regarded as the functional microspores, each of 

 which subsequently undergoes four mitoses so that they can be 

 said to germinate to a sixteen-celled gametophyte where each cell 

 functions as an antherozoid. In the macrosporangium the first four 

 nuclei formed are regarded as the functional megaspores, and each 

 of these is considered to germinate subsequently to a two-celled 

 female gametophyte where each cell functions as an ovum. In 



