154 PHAEOPHYCEAE 



merely develop into a new gametophytic generation. Sauvageau 

 also reported that the zooids from the unilocular sporangia may 

 give rise to creeping filaments which later produce young plantules 

 of Asperococciis. This direct reproduction of the macroscopic 

 plants can only be explained by a premature abnormal fusion of 

 some of the zooids from the unilocular sporangia. It will be 

 evident that direct alternation of generations is obscured in this 

 type through the number of possible independent circuits and 

 "short cuts". Recently the life cycle in Colpomenia sinuosa, a 

 member of a closely allied genus, has been described in detail (cf. 

 fig. 1 06). The adult plants are like Leathesia in appearance, although 

 they are essentially parenchymatous in structure. It will be seen, 

 however, that there are two morphologically similar generations, 

 the dioecious gametophytes appearing in spring and reproducing 

 by means of anisogametes that are formed in dissimilar gametangia. 

 The zygote gives rise to new adult asexual plants that reproduce by 

 means of plurilocular sporangia in autumn. 



REFERENCES 



Ectocarpus. Hamel, G. (1939). Bot. Notiser, p. 65. 

 Pylaiella. Knight, M. (1923). Trans. Roy. Soc. Edinb. 53, 343. 

 Ectocarpus. Knight, M. (1929). Trans. Roy. Soc. Edinb. 56, 307. 

 Asperococcus. Knight, M., Blackler, M. C. H. and Parke, M. W. 



(1935). Trans. Lpool Biol. Soc. p. 79. 

 Colpomenia. Kunieda, H. and Suto, S. (1938). Bot. Mag., Tokyo, 52, 



539. 

 General. Kylin, H. (1933). Lunds Univ. Arsskr. N.F. Avd. 2, 29, no. 7, 



p. I. 

 Ectocarpus. Papenfuss, G. (1935). Bot. Gaz. 96, 421. 

 Mesogloia, Castagnea, Acrothrix. Parke, M. W. (1933). Publ. Hart. Bot. 



Lab. no. 9. 

 Ectocarpus. Schussnig, B. and Kothbauer, E. (1934). Ost. Bot. Z. 83, 81. 

 Phyllitis. Yendo, K. (19 19). Bot. Mag., Tokyo, 33, 171. 



CUTLERIALES (ISOGENERATAE) 



This order is characterized by trichothallic growth, regular 

 alternation of generations, and a well-marked anisogamy which in 

 some respects approaches oogamy. They are generally placed in the 

 Isogeneratae, even though this leads to a difficulty because in 

 Cutleria the two generations are not equal morphologically 

 although they are equal in Zanardinia. On this classification, 



