Tetrasporese 



187 



Sub-family TETRASPORE/E. The Alga? comprised in this group are dis- 

 tinguished from all other members of the Palmellacese by the possession of 

 ' pseudocilia.' These are motionless, functionless cilia, each mature cell being- 

 provided with two or more. In Tetraspora the cells are largely grouped in 

 fours at the periphery of a more or less extensive (macroscopic) mucilaginous 



mt 



H 



Fig. 113. A G, Schizochlamys flelatinosa A. Br. A, vegetative cell showing pseudocilia, 

 y. 625 ; B, cell showing ecdysis of outer layers of wall, x 415 ; C and D, formation of 

 zoogonidia, x 625 ; E, zoogonidium, x 830 ; F and G, zoogonidium changing to Schizo- 

 chlamys-cell, x 830. H and I, Apiocystis Brauniana Nag. H, pear-shaped colony, x 430 ; 

 I, three cells showing pseudocilia, b, two daughter-cells from a division, the second pseudo- 

 cilium not yet developed, x 860. J, Tetraspora gelatinosa (Vauch.) Desv., periphery of 

 colony showing a few of the cells with their pseudocilia, x about 900. cv, contractile 

 vacuole ; n, nucleus; ol, oil globule; ps.c., pseudocilia; pij, pyrenoid ; st, stigma (or 

 pigment-spot). (A G, after Scherffel ; J, after Chodat.) 



colony. The cells multiply by repeated division, chiefly in two directions in 

 one plane, with the conversion of the walls of the mother-cells into mucilage. 

 The pseudocilia are embedded in the mucilage of the colony (fig. 113 J), and 

 each cell is of the Palmella-type, with a cup-shaped or a more or less 

 indefinite Chlamydomonadine chloroplast. In Apiocystis (fig. 113 H and /) 

 the colonies are relatively small, pyriform in shape, and usually attached by 



