«86 G. F. PAPENFUSS 



results of Eliding in his culture work on Enteromorpha sug- 

 gests that tlie equally troublesome genus Cladophora should be 

 studied along the same lines. 



A few accounts in the literature (see Hurd, 1916, pp. 117, 118) 

 indicate that the large swarmers of Codium may germinate di- 

 rectly at times. The question arises, are these cells female gametes 

 which develop parthenogenetically or are they zoospores? The 

 existence of the first condition would be of extreme interest in 

 view of the fact that Codium is a diploid alga, and the latter con- 

 dition would indicate that some species of Codium either mul- 

 tiply asexually by diploid zoospores or possess an alternation of 

 generations. 



As is well known, many of the species and varieties of Cauler- 

 pa intergrade to a degree that is perplexing to the systematist. 

 Dostal (1929, 1945) has shown not only that this genus can be 

 grown successfully in culture but that it lends itself to experi- 

 mental work. It thus appears likely that a cultural study of the 

 species will give a better indication of the degree of flexibility of 

 the various entities than can be obtained from observation of 

 plants from the sea alone. 



In the family Codiaceae, which comprises some seventeen 

 genera, reproductive organs have been observed in Codium and 

 Hcdimeda only. It seems likely that in the other genera, the re- 

 productive cells are formed in the undifferentiated thallus as they 

 are in Caulerpa. Constant observation of these plants in culture 

 may give an answer to this strange phenomenon. 



Phaeophyta^ 



Much of our knowledge of the life cycles of brown algae has 

 been acquired in comparatively recent times. In general, this in- 

 formation was not forthcoming until it had been shown that the 

 complete cycle of development could not be learned unless the 

 plants were grown in culture. To Sauvageau, especially, we are 

 indebted for leadership in this approach to problems relating to 

 the life cycles of brown algae. Among botanists in general he is 



'^ See footnote, p. 79. 



