PAPENFUSS: CLASSIFICATION OF THE ALGAE 189 



Family Rhodomelaceae (J. Agardh) Harvey (1849, p. 74) 



Syn.: Laurenciaceae Harvey (1849, p. 74); Rytiphlaeaceae Kutzing 

 (1843, p. 442) 



Prospect 



From the preceding review it will be evident that knowledge of the structure 

 and reproduction of the algae, and hence of their classification, has advanced 

 tremendously during the past hundred years. It is now well established that the 

 assemblage of plants referred to as algae is comprised of a number of only dis- 

 tantly related groups of organisms that share few characters except the ability of 

 most of the forms to synthesize organic compounds by the process of photo- 

 synthesis and the absence of a primarily produced jacket of sterile cells about 

 the reproductive organs. 



If the bases of the present systems of classification of the members of the 

 major groups are examined, however, it is found that not infrequently families 

 and even orders have been established on the strength of knowledge obtained 

 from a study of only a few species or in certain instances only one species. Ob- 

 viously there exists a great need for detailed information on a large number of 

 genera and species before it will be possible to erect schemes of classification 

 that will portray in a reasonably accurate way the phylogenetic affinities of the 

 organisms that constitute these groups. It is no exaggeration to say that only a 

 good beginning has been made in the sorting out of the natural subdivisions 

 of the major taxa. 



Biochemical information has contributed much to a better understanding 

 of the interrelationships of various groups of algae. It is to be expected that 

 biochemical investigation of the many forms that have not yet received atten- 

 tion will yield knowledge that will be as significant as that obtained in the past. 



Although the chromosomes of algae are generally small and hence do not 

 lend themselves well to karyological study, cytotaxonomic investigations like 

 those of Cave and Pocock (1951) encouragingly point to the rich rew\ards that 

 may be expected from the pursuit of problems in this largely unexplored area. 



In recent years electron microscope studies have yielded valuable informa- 

 tion on the structure of the flagella and the cell wall of diverse algae. The inter- 

 esting new facts brought to light augur well for an expanding use of this tool 

 in algal research. 



In the past, knowledge of the developmental morphology and the life his- 

 tories of algae has contributed greatly toward the elucidation of phylogenetic 

 affinities among these plants. Pressing needs exist for information of this kind 

 on many more species. In numerous instances progress in life-history studies 

 has been greatly retarded and not infrequently the results have been woefully 

 fragmentary owing to the difficulty of obtaining germination stages of the zygo- 

 spores or other resting cells. It may be anticipated that in the future the physi- 

 ology of resting cell maturation and germination will receive the attention that 

 it merits and that the knowledge gained will make it possible to induce these 

 cells to mature and germinate at will. An understanding of tlie physiology of 

 resting cell germination will not only aid in life-history studies but will be a 

 tremendous impetus to the full utilization of these simple autotrophic plants as 

 material in experimental studies, 



