CULTURE AND MORPHOLOGY 9?' 



The use of cultures most likely will assist in finding an ex- 

 planation of a variety of other important questions relating to the 

 life cycles of red algae. For example, in the family Acrochaetia- 

 ceae of the order Nemalionales, certain species form only sexual 

 organs and monosporangia whereas others produce only tetra- 

 sporangia. As has been pointed out by Papenfuss (1945), it is not 

 improbable that some of these species represent a generation in 

 the life cycle of others; but this can be determined only from 

 cultural and cytological studies. 



Among the larger red algae, many of which are common and 

 have been under observation for a long time, there are likewise 

 species which appear to be represented in nature either by sexual 

 individuals only (several Dumontiaceae, Schizymenia^ and oth- 

 ers), or by asexual individuals only {Halosaccion, Hildenbrandia, 

 and others). Promise of an ultimate solution to some of these 

 peculiar phenomena is furnished by the excellent results of 

 Dammann (1930) in her study of Halarachnion ligulatum 

 (Woodw.) Kutz. No certain records exist of the occurrence in 

 nature of tetrasporangial plants of diis species. Nonetheless they 

 were obtained by Dammann in cultures which were started from 

 carpospores. 



In many respects only a beginning has been made in the cul- 

 tural approach to problems in the red algae. In this review,, 

 brief mention has been made of some of the work that has been 

 done and a few of the problems that might be studied by this 

 method of attack. Although consideration has been given only to 

 questions which directly bear upon the life cycles and indirectly 

 on the systematics of red algae, the usefulness of members of this 

 group in experimental studies should be explored also. The 

 majority of red algae include three generations in their life cycle: 

 a haploid gametophyte, a diploid carposporophyte which is para- 

 sitic on the gametophyte and a free-living, diploid tetrasporo- 

 phyte. It would be of great interest to see whether the young 

 carposporophyte would grow in culture and, if it does, whether 

 it is capable of producing a tetrasporophyte directly. 



