50 
Gonyostomum Semen Diesing. 
is about the same length as the body of the cell. The trailing 
backwardly directed flagellum vibrates in the ventral groove 
and the flickering due to this vibration was clearly seen 
in cells viewed when turning over. (Fig. 5). The organism 
normally swims steadily forward, grooved side downwards, 
without any spiral turning motion, such as is characteristic 
of Chlamydomonas. Sudden backward movements are 
frequent. 
In the fresh cell the chromatophores are not visible as 
clearly separated bodies, but treatment with very dilute 
iodine causes the cell to round off and to discharge its refractive 
rods, which lengthen somewhat on discharge. During this 
change the chromatophores are revealed as clearly separate 
green bodies. In such a rounded cell their shape is round, 
but when occasionally visible in the fresh living cell, they are 
more elongated. Fig. 2 shows their distribution in a cell 
which, though not fully rounded off, yet shows them clearly. 
Continued action of iodine causes the cell to disintegrate 
and, as it does so, the chromatophores are discharged from the 
cell and are seen outside mixed with small oil glubu'les, oil 
being an assimilatory product of this organism. In these 
iodine treated cells the nucleus becomes clearly visible. It 
is large, and in a dying individual which had rounded off to 
dimensions of 41 ju X 35 u, the nucleus measured 18 g X 11 g. 
It possesses a small nucleolus. Irritation by iodine apparently 
causes the dense, taut periplast to slacken and thin out, and 
this, together with the fact that the rods have been got out 
of the way by discharge, clearly reveals the chromatophores 
as separate bodies. Owing to its extreme susceptibility to 
irritating liquids, the organism cannot easily be preserved, 
as it disintegrates very quickly in all the media so far tried. 
Figs. 6 and 7 show two views of the vacuole system at the 
anterior end. There is one large three-angled vacuole opening 
anteriorly to the outside and in another plane rounded 
diverticula of this can be seen. The central space and the 
diverticula slowly change their relationships so as to look at 
one time almost separate, at another time united. The cell 
is slightly metabolic. When unimpeded, it swims smoothly 
forward and the normal shape, as then shown, is not curved. 
It is found in still pools among Sphagnum , and is most 
common in pools with a good deal of free water with some 
Sphagnum. Pools in which filamentous algae are abundant 
do not contain it. Small quantities of Microspora tumidula 
and Cocystis solitaria, however, accompany it among the 
bogmoss. Pascher 2 records it as widespread yet occasional 
on the continent in stagnant water and peaty pools. No 
reproductive stages were observed. 
2 Loc. cit. 
The Naturalist 
