Recorp of the occurrence, new to Irevann, with Nors, of a 
Peculiar Condition of the Votvocinacrous ALGA, STEPHA- 
NOSPHARA PLUVIALIS (Cohn), and Observations thereon. 
By Witiiam Arcuer.* 
(Continued from p. 132.) 
Iv may be said that the primordial cells of the mature 
plant do not change place within the envelope-cell ; but there 
are circumstances, even though the force were more energetic 
than it at all can be, which prevent this. The pair of flagelli- 
form cilia projecting through the extremely minute openings 
in the wall of the primordial cell into the water, and the 
majority of the protoplasmic prolongations reaching to con- 
tact with its inner surface, where they doubtless for a time 
adhere, tend to suspend the primordial cell in its place. But 
even when these are not fully extended, and besides the 
slowness and comparative feebleness of the process, the pro- 
longations existing at opposite ends simultaneously and the 
contents being of a compact and comparatively firm character, 
not loose and disintegrated as afterwards, as evinced by the 
constancy in position of the two “ chlorophyll-vesicles,” there 
is no flow in any direction of the contents, nor any reptant 
motion. There is, I think, to some degree, a certain amount 
of foreshadowing, as it were, of the differentiation of the 
extremities, so conspicuous in my amoeboid bodies, in the 
ordinary primordial cells; it will be noticed that these are 
often far more copiously drawn out into the described fila- 
mentous prolongations at one end than at the other, which 
is more attenuated; and one end of each of the primor- 
dial cells is often drawn much more into one hemisphere of 
the globe than the other. 
Now, the foregoing remarkable considerations seem to have 
excited comparatively little notice ; and it is only when such 
characteristics are evinced so forcibly as that the primordial 
cells crawl rhizopod-like about that they strike us with 
wonder. The amceboid bodies described become propelled 
constantly in one direction, because the pseudopodal processes 
are given off only at one extremity, and the influx of the 
granular substance of the mass is, of course, obliged to 
follow in that direction. 
But the assumption by the primordial cells of Stephano- 
sphera of an ameeboid condition is not without a parallel in 
another volvocinaceous alga. Dr. Hicks has described an 
amceboid condition of the “ zoospores” of the far more 
* Read before the Natural History Society of Dublin, May 6, 1863. 
