188 



Tetrasporinede 



the base to other larger Algae. The cells are disposed without any definite 

 order near the periphery of the mucilaginous colony. The pseudocilia are very 

 long and project through the mucus into the surrounding water. The cells 

 divide in two or three directions in the peripheral plane. In this division 

 one pseudocilium goes to each daughter-cell, a second one being subsequently 

 developed (Correns, '93). The genus Schizochlamys has recently been shown 

 by Scherffel ('08 B) to belong to this group, and each vegetative cell before 

 it begins its characteristic ecdysis of the older parts of the wall (fig. 113 E} 

 possesses a number of long pseudocilia (fig. 113 A). Both starch and oil 

 occur as reserves in this genus. McAllister (13) has observed the entire 

 pyrenoid of Tetraspora lubrica segment to form several starch -bodies. 

 Reproduction takes place by biciliated zoogonidia and isoplariogametes in 

 Tetraspora and Apiocystis, and by biciliated or quadriciliated zoogonidia in 

 Schizochlamys. Aplanospores (hypnospores) are also known in all these genera. 



All the genera occur in fresh water ; they are : Apiocystis Nageli, 1849 ; Schizochlamys 

 A. Braun, 1849 ; Tetraspora Link, 1809 [inclus. Stapfia Chodat, 1897] ; ? Tetrasporidium 

 Mobiiis, 1893. 



Sub-family PALMOPHYLLE^E. The two genera of this group are charac- 

 terized by their macroscopic colonies, the mucus of which presents a firm 

 outer layer. The colonies have in consequence somewhat definite shapes: they 



D 



Fig. 114. Collinsiella tuberculata Setch. & Gardn. A, general appearance of colonies, x 35 ; 

 B, section through colony, x about 150 ; C, surface view of cells, x 300 ; D, single cell from 

 the side, x about 700. (After Setchell & Gardner, from Wille.) 



are tuberculate in character in Collinsiella, and expanded and leaf-like in 

 Palmophyllum. In the first-named genus the cells are chiefly aggregated 

 towards the periphery, and there are obvious indications that the mucus is in 

 reality a fusion of the mucilaginous stalks of a branched colony of cells. 

 Division of the cells takes place in two directions at right angles to each other 

 and to the surface of the colony (fig. 114). In Palmophyllum division of the 



