186 A CENTURY OF PROGRESS IN THE NATURAL SCIENCES 



do not seem to be of sufficient magnitude to justify recognition of a separate 

 order. 



Oltmanns (1904) brought into focus an anatomical character that has proved 

 of great importance in the classification of the Florideophycidae. He empha- 

 sized that in some genera the thallus has a uniaxial construction whereas in 

 others it is multiaxial. Kylin (1928, 1930a, and especially 1932) has made very 

 effective use of this character in the separation of families. 



We are especially indebted to Kylin for the refinement of Schmitz's embryo- 

 logical system of classification of the Florideophycidae. In a long series of 

 papers, especially the monographic studies of 1923, 1928, 1930a, and 1932, he 

 has immensely advanced our knowledge of the comparative morphology of 

 these algae and has thereby contributed more than any other one person to a 

 better understanding of the interrelationships of this large and diversified phy- 

 lum. Despite certain shortcomings (see Papenfuss, 1951b) his system of 1932 

 allows of a much more natural arrangement than had previously been possible. 

 It is the standard one today. 



In Kylin's system the orders are separated on whether or not "typical" 

 auxiliary cells (generative auxiliary cells of Papenfuss, 1951b) are absent or 

 present, their time of formation — before or after fertilization — and their man- 

 ner and place of formation. Within the orders, the families are separated on 

 whether the thallus is uniaxial or multiaxial, whether the cystocarp is imbedded 

 in the thallus or not, whether the tetrasporangia are tetrahedrally, cruciately, 

 or zonately divided, and various other characters of seemingly comparable 

 importance. 



In regard to the long-standing disagreement between Svedelius and Kylin 

 as to whether the Nemalionales do or do not possess a "typical" auxiliary cell 

 reference should be made to the papers by Martin (1939), Svedelius (1942), 

 and Kylin (1944b). In the opinion of Kylin, the cell or cells in the nemaliona- 

 lean carpogonial branch that receive a diploid nucleus from the fertilized carpo- 

 gonium and from which the gonimoblast develops do not constitute a "typical" 

 auxiliary cell; yet he has no hesitation in considering the supporting cell in the 

 Kallymeniaceae (Cryptonemiales) and in Sphaerococcus (Gigartinales) as a 

 "typical" auxiliary cell, even though it is a cell in the carpogonial Ijranch system. 



Brief mention should be made of two groups of red algae which at first were 

 not associated with this phylum. The first of these, the Corallinaceae, were for 

 a long time, along with other calcified algae, regarded as corals. S. F. Gray 

 (1821) appears to have been the first botanist to have considered them algae, 

 without qualification, but they did not receive general acceptance as red algae 

 until Decaisne (1842b) showed that they possess the typical features of this group. 



Despite their purple color the members of the other group, the subclass 

 Bangiophycidae, were for many decades after they had become known classified 

 with the filamentous or membranous green algae which they resemble in habit. 

 As recently as 1922 Oltmanns (1922b, p. 230) stated that he was not fully con- 

 vinced that these forms really belong with the Rhodophyceae. Although Thuret 

 {in Le Jolis, 1863) and Rabenhorst (1868) had associated these forms with the 

 Rhodophyceae, their place among the latter remained uncertain until the ap- 

 pearance of Berthold's (1881a, 1882) critical investigations of various members 

 of the group. 



