257 
Notes on Freshwater Algce. 
Under unfavourable conditions the organism readily assumes 
the “ Palmella ’’-state. The cilia are lost and the cells assume 
various irregular shapes, hut generally tend to become more or 
less sub-globose, the anterior lobes become usually unrecognisable, 
and the outlines of the chloroplast very indistinct, although stigma 
and pyrenoid persist, and the contractile vacuoles become more 
apparent (Fig. 1, F). Around each cell there develops a thick 
hyaline gelatinous investment (g in Fig. 1, F), and numerous cells 
often become aggregated together in a common jelly. 
These non-motile cells can undergo slow change of form. 
Griffiths (l.c. p. 134) states that no amoeboid alterations in the shape 
of the cell was observed in P. delicatulus , and further remarks 
that “ in this respect Pyramimonas appears to differ from the other 
members of the Polyblepharidacese.” West, 1 writing of the 
Polyblepharidacese, states that “ the body of the cell is invested 
only by a protoplasmic membrane and, with the possible exception 
of Pyramimonas , is able within prescribed limits to undergo certain 
changes of form.” These two statements concerning Pyramimonas 
are, however, true only in the case of P. delicatulus , since Dill in 
his account ofP. tetrarhynchus (the third known member of the genus) 
says “ Wahrend der Bewegung sowohl als in der Ruhe konnte ich 
an diesen Organismen Formveranderungen wahrnehmen.” 2 Dill 
also quotes Dangeard (Le Botaniste 1889, p. 138) as having 
observed alteration of form (“ metabolie ”) in P. tetrarhynchus. 
Division of the cell is longitudinal, and takes place in motile 
as well as non-motile (encysted) individuals, the process of 
division resembling that described by Griffiths in the case of P, 
delicatulus. It commences at the posterior end of the cell, and 
gradually extends anteriorly. In the case of motile cells the cilia 
increase in number to eight prior to cell-division, each daughter 
cell retaining four. 
This species (termed P. inconstans on account of the 
variability in form of -the cell) differs from both P. tetrarhynchus 
Schmarda 3 and P. delicatulus Griffiths (1. c.) in the smaller size 
of its cells, the non-lobed chloroplast, and the anterior stigma. 
From the last-named species it further differs in having no 
posterior excavation in the chloroplast. The anterior lobes of the 
cells of P. inconstans are also much less developed than those of 
1 West, G. S.. Algae, Vol. I. Camb. Univ. Press, 1916, p. 164. 
* Dill, O. E., Jahrb. f. wiss. Bot., XXVIII. 1895, p. 344. 
8 Described by Dill, 1. c. 
