PROGRESS AND ACHIEVEMENTS IN PHYCOLOGY 563 



PYRROPHYCOPHYTA 



With few exceptions (e.g., Pyrocystis) the dinoflagellates that had become 

 known to science previous to 1912 were flagellated forms. In that year Klebs 

 published his significant discovery of several nonmotile unicellular organisms 

 that at certain stages in their development clearly revealed their relationship 

 to the dinoflagellates. Two years later Pascher (1914) announced the dis- 

 covery of a number of additional nonmotfle types and also proposed a far- 

 reaching revision of the classification of the dinoflagellates. Some of the non- 

 motile types have a palmelloid organization (Pascher 's Dinocapsales), others 

 have a coccoid organization (his Dinococcales), and the single representative 

 of a third group has a filamentous organization (his Dinotrichales). 



CONCLUSION 



Fifty years ago botanists customarily recognized a phylum Thallophyta 

 which received the algae and the fungi. Few, if any, mycologists and phycolo- 

 gists would today be willing to accept such a heterogeneous phylum. 



Fifty years ago the algae were usually divided into about nine classes. On 

 the basis of pigment composition, nature of food reserves, structure of the 

 cell, t)qDe of flagellation, structure of the flagella, structure of the reproductive 

 organs, and method of reproduction, the algae are today arranged in seven 

 or more phyla and, in addition, several classes of uncertain systematic position. 



In this paper reference has been made to only a few of the advances in 

 knowledge that have led to this new classification — in fact, several of the 

 major groups were entirely omitted from consideration. To the non-algologist 

 it may appear that the present system of the algae has been made unduly 

 complex by the recognition of an excessively large number of major taxa. It 

 should be made clear that there is great unanimity among phycologists about 

 this system. We may differ as to whether the cryptomonads and chloromonads 

 should be regarded as classes of uncertain systematic position or as autono- 

 mous phyla, on whether the charophytes should be considered a class in the 

 green algae or a separate phylum, on whether the blue-green algae should 

 be placed together with the bacteria in a phylum Schizophyta or whether 

 they constitute an independent phylum, and other such questions, but on 

 the underlying principles of the system we show remarkable agreement. 



LITERATURE CITED 



Abbott, Isabella A. 1945. The genus Liagora (Rhodophyceae) in Hawaii. Bishop 

 Mus. Hawaii Occasional Papers 18:145-169. 



