PROGRESS AND ACHIEVEMENTS IN PHYCOLOGY 559 



instead of occurring immediately after fertilization, has been delayed until the 

 formation of carposporangia. This condition is of considerable phylogenetic 

 interest, for it illustrates a probable intermediate step in the evolution of 

 the triphasic type of life history characteristic of the bulk of the higher red 

 algae. A further postponement of meiosis would of course result in diploid 

 carpospores, which on germination and mitotic division of the nucleus would 

 produce diploid free-Hving tetrasporophytes. 



On the other hand, there are genera of higher red algae, such as Phyllophora 

 (Rosenvinge, 1929; Claussen, 1929; Kylin, 1930) and Gymnogongrus 

 (Chemin, 1933; Gregory, 1934; Doubt, 1935), which include species with a 

 diphasic life history similar to that of the species of Liagora and Helmintho- 

 cladia considered above. In these the diphasic condition clearly appears to 

 be derived, having come about as the result of an advancement of meiosis to 

 the time of carpospore formation and the consequent elimination of the free- 

 living tetrasporophyte. Feldmann (1952) and others have expressed the opin- 

 ion that all Florideophycidae that lack a free-living tetrasporophyte may be 

 derived, but Svedelius (1956) has produced convincing evidence that this is 

 not always so. 



Attention should also be brought to the very interesting observations (made 

 on the basis of cultures) by J. and G. Feldmann, Drew, Koch, Tseng and 

 Chang, and others. J. and G. Feldmann (1942 and earlier papers) have ob- 

 tained results which indicate that H ymenocloniuni serpens and Falkenbergia 

 rujolanosa represent filamentous tetrasporangial phases in the life histories 

 of Bonnemaisonia asparagoides and Asparagopsis arnuita, respectively, and 

 that Trailliella intrkata probably represents a filamentous tetrasporangial 

 stage in the life history of Bonnemaisonia hamijera. That a relationship actu- 

 ally exists between T. intricata and B. hamijera has recently been demon- 

 strated by Koch (1950). Bonnemaisonia and Asparagopsis thus display a 

 triphasic life history in which the free-living tetrasporophyte is morphologically 

 very different from the gametophyte. 



In the Bangiophycidae, in which to the best of our knowledge all the cells 

 except the zygote are haploid (as in many Nemalionales of the Florideo- 

 phycidae), Drew (1949, 1954b) and Tseng and Chang (1955) have shown 

 that the filamentous, shell-inhabiting forms previously known as Conchocelis 

 rosea are a stage in the life history of both the membranous Porphyra and the 

 ribbon-like Bangia. The establishment of the existence of an intimate relation- 

 ship between Conchocelis and these two genera is a matter not only of botani- 

 cal significance but of considerable economic importance in those parts of 

 the world where Porphyra is cultivated for food. 



We are indebted to Kylin for the refinement of Schmitz's (1883) em- 

 bryological system of classification of the main group of red algae, the Florideo- 

 phycidae. In a long series of papers, especially the monographic works of 

 1923, 1928, 1930, and 1932, he immensely advanced our knowledge of the 



