Flagellata and Primitive Algcz. 183 
same gradually coming to rest and about to lose its flagella ; 7, the same after 
loss of flagella, secreting a drop of mucilage for attachment; 8, the same, two 
days later (the transverse furrow which had disappeared on coming to rest 
has now been re-formed). 9, 10, Glenodinium pulvisculits Ehrb.: in 10 one of the 
shell-valves has been forced off to allow escape of the spore, which soon 
afterwards undergoes division. 11 to 13, Glenodinium emavginatum Klebs: in 11 
the cell contents have undergone oblique longitudinal division ; 12 shows 
escape of contents as a spore (cyst), and 13 the division of this cyst. 14, 
Spirodinium spirale (Bergh) Schiitt. 15, 16, Cochlodinium strangulation Schott. 
17, Pouchetiu fusus Schiitt, showing the spirally coiled flagellum grooves, and 
the stigma (consisting of a pigment-body with a refractive lens-like body on 
either side of it. 18, 19, Polykvikos auvicularia Biitschli : in 18 the longitudinal 
flagellum groove, eight transverse grooves, four nuclei, and five trichocysts ; 
19, a trichocyst. 20 to 26, Cystodinium bataviense Klebs : 20, cyst with Peridinean 
body ; 21 to 23, stages in division of cyst contents into two cells, which escape 
by gelatinisation of one side of the cyst (seen in 24) ; 25, motile cell; 26, motile 
cell has become a cyst, set free by rupture of the cell-wall ; the black fleck in 
20, 22, and 25 is a stigma (“eye spot ’’). 27 to 34, Diplodinium lunula (Schiitt) 
Klebs (= Pyrocystis lunula Schiitt) : 27, uninucleate primary cyst; 28, cyst with 
four nuclei, the cytoplasm not yet divided ; 29, cyst with four cells, each about 
to divide again ; 30, sickle-shaped secondary cyst; 31, contraction of contents 
of same ; 32, 33, division of contents into motile Gymnodiniunt-UWe cells, of 
which one is shown more highly magnified in 34. 35 to 40, Hypnodinium 
spluevicum Klebs; 35, a cell in optical section, showing the central nucleus, the 
numerous small chromatophores in the peripheral and radiating portions of 
the cytoplasm, an “eye spot,” and five orange-red oil drops; 36, cell with 
rounded off contents showing Gymnodinium- like grooves ; 37, stage in division, 
showing two nuclei, two transverse grooves, and two “ eye spots” ; 37, division 
into two Gymnodinium-Uke cells completed ; 39, 40, rupture of cyst, setting free 
the two daughter cells, which have now lost their grooves. 
1, 9, 10, from Stein ; 2 to 8, 11 to 13, 20 to 26, 35 to 40, from Klebs; 14 to 
17, from Schiitt; 18, 19, from Bergh. 
forms, there appears to be little doubt that the discovery of 
Protochrysis has at any rate lessened the gap between the Crypto¬ 
monads and a simple Peridinean genus like Hemidinium with its 
incomplete transverse groove. From a form like Hemidinium, the 
transition is easy to Gymnodinium and to Glenodinium (which is 
best placed in the Gymnodiniacese and which forms a connecting 
link with the Ceratiaceae). These simple Gymnodiniaceae form a 
central group from which diverge lines leading in various directions. 
In Spirodinium, Cochlodinium, and Pouchetia the cell is elongated 
and the grooves spirally coiled, and the pigmented body (stigma) 
found in the simpler forms is accompanied in Pouchetia by one or 
more lens-like bodies. In Pouchetia armata (Dogiel, 41) the cell is 
provided with nettling organs (trichocysts) consisting of a conical 
capsule containing a coiled stinging thread. Nettling organs of this 
kind are also found in the remarkable naked holozoic genus 
Polyhrikos (Biitschli, 18; Kofoid, 72), in which the elongated body 
has eight transverse grooves and a single straight longitudinal groove, 
and there are eight nuclei—according to Delage (37) these are 
meganuclei, accompanied by smaller nuclei (micronuclei) as in 
Ciliate Infusoria, and each transverse groove has a flagellum. 
From Kofoid’s account of Polyhrikos, it would appear that the 
apparently single cell is a colony of individuals arranged in a linear 
series, owing to incomplete separation after division; Dogiel (41) 
has described specimens with four transverse grooves and a single 
nucleus. Polyhrikos may be definitely placed in the Gymnodiniaceae, 
since the presence of nettling organs in Pouchetia connects it with 
Cochlodinium and Spirodinium and thus with the simpler genera 
