472 SMITH 



Early in the nineteenth century phycologists began to have the temerity to 

 describe genera additional to the sacred four recognized by Linnaeus. New 

 genera appeared in the literature at a rapid rate, and many of the earlier 

 established genera were divided into two or more genera. With the establish- 

 ment of a number of genera there came the grouping of them into taxa of 

 higher categories. Lamoroux (1813) was the first to do this. He placed marine 

 algae in a "family" he called the Thalassiophytes and divided this family 

 into six "orders," the three most important being the Fucacees, Floridees, and 

 the Ulvacees. Distinctions between these taxa were made in part, but not 

 exclusively, upon color. The next significant grouping into major taxa was 

 proposed by Harvey (1836, 1841) when he divided algae into four "series" 

 (Melanospermeae, Rhodospermeae, Chlorospermeae, Diatomaceae), each with 

 a number of families. Distinction between the first three was made on the 

 basis of their brown, red, or green color. This distinction on the basis of color 

 has stood the test of time and has been found to be correlated with distinctive 

 types of reproductive structure. The names Harvey applied to his major taxa 

 were soon supplanted by other names, the Melanospermeae being called the 

 Phaeophyceae, the Rhodospermeae called the Rhodophyceae, and the Chloro- 

 spermeae called the Chlorophyceae. Harvey's Diatomaceae included both 

 desmids and diatoms, but it was soon realized that desmids belonged among 

 the Chlorophyceae. 



The major taxon variously called Chlorospermeae or Chlorophyceae also 

 included blue-green algae. These were first segregated by Stizenberger (1860) 

 in a separate taxon that he called the Myxophyceae. Somewhat later Luther 

 (1899), primarily on the basis of flagellation of motile reproductive cells, 

 segregated certain of the supposedly grass-green algae into a class that he 

 called the Heterokonteae (Xanthophyceae). 



Until the beginning of the present century the flagellates with chromato- 

 phores of various colors were considered protozoa, and almost all our knowl- 

 edge concerning them was due to the efforts of protozoologists. An exception 

 must be made in the case of the Chlamyd&monas-V olvox series. For nearly 

 a century botanists have placed this series among the Chlorophyceae. Be- 

 ginning more than three quarters of a century ago botanists were in general 

 agreement that the Chlorophyceae have arisen from a unicellular flagellated 

 organism of the chlamydomonad type. Many also thought that the flagellated 

 reproductive cells of the Phaeophyceae indicate that they have arisen from 

 a unicellular flagellated ancestor. Correlated with this was the gradual appear- 

 ance of the view that flagellates related to unquestionable algae should be 

 placed among the algae instead of being placed among the protozoa. Although 

 not the pioneer in this idea, Pascher was the chief advocate of it and the 

 discoverer of many new algae obviously related to pigmented flagellates. 



For some time certain botanists had held that the dinoflagellates should 

 be considered algae. Their argument was based on the discovery of certain 



