136 A CENTURY OF PROGRESS IN THE NATURAL SCIENCES 



time, he divided the Flagellata into the five subgroups Protomastigina, Poly- 

 mastigina, Eugienoidina, Chloromonadina, and Chromomonadina. The Eu- 

 glenoidina he divided much as he had in 1883 except that he elevated the group 

 Astasiae to the rank of family and he now definitely accepted the Peranemeae 

 as a third family in the assemblage. 



As a group of plants, the Flagellata were treated by Senn (1900) in Engler 

 and Prantl's Pflanzenfamilien. He divided the Flagellata into seven subgroups 

 as follows: Pantostomatineae, Protomastigineae, Distomatineae, Chrysomona- 

 dineae, Cryptomonadineae, Chloromonadineae, and Euglenineae. 



In accordance with the classification of Klebs (1892), but in conformity with 

 botanical nomenclature, Senn divided the Euglenineae into the three families 

 Euglenaceae, Astasiaceae, and Peranemaceae. In 1903 {in Engler, 1903), he 

 treated the Flagellatae as a division and the seven groups named above as orders. 

 In his treatment of the euglenids in Pascher's Silsswasser-Flora . . . , Lemmer- 

 mann (1913) accepted the three families proposed by Klebs. 



Pascher in 1931 (p. 322) formally recognized the Euglenineae as an autono- 

 mous phylum of plants, the Euglenophyta. Smith (1933) established the family 

 Colaciaceae for the genus Colacium and later (1938) created for it the order 

 Colaciales. According to Jahn (1951) the removal of Colacium to a group of 

 its own is well warranted. 



The three families (Euglenaceae, Astasiaceae, Peranemaceae) that comprise 

 the Euglenales are largely separated on the basis of method of nutrition al- 

 though morphological characters (especially plastid structure, presence or ab- 

 sence of pyrenoids and nature of flagellar apparatus) are also utilized (cf., 

 Pringsheim, 1948a; Jahn, 1951). The family Euglenaceae includes all the chloro- 

 phyll-containing genera and those colorless forms that appear to be derived 

 from green species. The Astasiaceae are saprophytic and the Peranemaceae are 

 holozoic. It is generally agreed by students of the group that the classification 

 of the Euglenales is artificial but for practical reasons the separation into three 

 families has been adhered to pending further knowledge of the complex. The 

 autonomy of Astasia and certain other colorless (saprophytic) forms is espe- 

 cially doubtful (cf., Pringsheim, 1948b, 1952). 



The order Colaciales embraces the single chlorophyll-containing genus Cola- 

 cium. The individuals are nonmotile in the vegetative phase and are surrounded 

 by a gelatinous sheath affixed to components of the freshwater zooplankton. 

 Usually the individuals produced by division secrete a stalk of their own and 

 these stalks remain attached to the stalk of the parent cell. As a result of re- 

 peated cell division there is thus formed a dendroid colony with the cells at 

 the terminations of the dichotomously branched stalk system. 



As a group, the Euglenophycophyta constitute a highly specialized and seem- 

 ingly isolated assemblage with no clear alliance to other flagellated organisms. 

 The literature on the phylum may be traced through the bibliographies of 

 Fritsch (1935), Jahn (1946, 1951), Pringsheim (1948a), and Pringsheim and 

 Hovasse (1950). 



A synoptic arrangement of the orders and families follows. 



Phylum EUGLENOPHYCOPHYTA Papenfuss (1946, p. 218) 

 Syn.: Euglenophyta Pascher (1931, p. 322) 



Class EuGLENOPHYCEAE G. M. Smith (1933, pp. 4, 607) 



