CULTURE AND MORPHOLOGY 87 



perhaps best remembered for his epoch-making discovery in 1915 

 of an alternation of heteromorphic generations in members of the 

 order Laminariales. Over a period of some thirty years previous 

 to his death in 1936, he contributed a long series of important 

 papers on the ontogeny of a large number of brow^n algae. 



In 1933 Kylin published a paper which formed an important 

 landmark in the advancement of knowledge of the brown algae. 

 In addition to contributing new information on the life cycles of 

 some of these plants, he utilized the available knowledge of their 

 structure and reproduction to establish a new system of classifi- 

 cation. 



In earlier systems, the classification of the higher categories 

 of brown algae was largely based on structure. Although struc- 

 ture is still of great importance in the separation of related spe- 

 cies, genera, families and in a few instances even orders, the 

 system of Kylin offered a notable departure in that it was to a 

 large extent based upon life cycle. In view of the transcendent 

 value of the type of ontogeny as an indicator of phylogenetic 

 affinities in lower organisms, the system of Kylin must be consid- 

 ered as portraying more accurately the basic relationships among 

 brown algae than do earlier systems. 



On the basis of life history, Kylin divided the Phaeophyta into 

 three classes: Isogeneratae, Heterogeneratae and Cyclosporeae. As 

 the names imply, the class Isogeneratae includes forms which 

 show an alternation of isomorphic generations and the Hetero- 

 generatae comprise forms which possess an alternation of hetero- 

 morphic generations, with the sporophyte usually macroscopic 

 and the gametophytes microscopic in size. The Cyclosporeae 

 include the single order Fucales, the members of which lack an al- 

 ternation of generations. The plants are diploid and meiosis occurs 

 at gametogenesis. Kylin placed five orders (Ectocarpales, Sphace- 

 lariales, Cutleriales, Tilopteridales and Dictyotales) in the Iso- 

 generatae and six in the Heterogeneratae (Chordariales, Sporoch- 

 nales, Desmarestiales, Punctariales, Dictyosiphonales and Lam- 

 inariales). However, Papenfuss (1947) has included the Punc- 

 tariales in the Dictyosiphonales. A diagrammatic representation 

 of the slightly modified system of Kylin is given in figure 5. 



