402 ffeterokontas 



It is a noteworthy fact that there are no highly developed reproductive 

 organs, or even differentiated reproductive cells, in any family of the group. 



Bohlin, in two excellent papers ('97 ; '01 A), strongly emphasized the importance of 

 maintaining the group of the Heterokontse, but in completely separating the group from 

 all other Green Algae he was just as much in error as was Wille in separating the 

 Conjugates from the rest of the Chlorophycese. Blackman & Tansley ('02) and also 

 West (G. S. W., '04) supported Bohlin's views, the former even to the extent of including 

 the Vaucheriaceae in the Heterokontae (vide p. 249). 



Concerning the classification of the Heterokontse there is no doubt that 

 the old order ' Confervales/ which embraced all but the Flagellate forms, was 

 much too wide in its scope and cannot in future be retained. A number 

 of suggestions have recently been put forward by Pascher ('13 B; '14) and it 

 is necessary that they should be carefully considered. In his first paper in 

 1913 he subdivided the Heterokontae into five groups which he regarded as 

 equivalent to corresponding groups in the Chlorophyceae (= Isokontae of this 

 work). They may be briefly summarized as follows : 



Heterokontw Chlorophycede. 



(of Pascher) 



Heterochloriadales Volvocales 



Heterocapsales Tetrasporales 



Heterocapsaceae 



? Botryococcaceae 



MischococcaceaB 

 Heterococcales Protococcales 



Chlorobotrydaceae 



Sciadiaceae 

 Heterotrichales Ulotrichales 



Tribonemaceae 

 Heterosiphonales Siphonales 



In his later paper, in 1914, Pascher widely separated the Heterokontae 

 from the ' Chlorophycea3,' placing the latter along with the Conjugate in 

 a new primary group, the Chlorophyta, and the former, along with the 

 Chrysophyceae and Bacillariales, in another new group, the Chrysophyta. 

 The correlated scheme of arrangement of the ' Chrysophyta/ ' Pyrrophy ta ' 

 (which includes the Peridinieae and the Cryptomonadales) and ' Chlorophyta,' 

 as set forth by Pascher, is very methodical, but the scheme must be considered 

 in the light of facts. There is little, if any, reason for separating the 

 Heterokontae so decisively from the remainder of the Green Algae that two 

 of the intervening groups are the ' Phaeophyta ' (which is presumably a new 

 name for the Phaeophyceae) and the * Pyrrophyta.' Moreover, a large part of 

 the scheme depends upon the supposed validity of the ' Volvocales/ ' Tetra- 

 sporales ' and ' Protococcales ' as independent orders. In this work a division of 

 this kind cannot be admitted, since the complete separation of such groups 



