ARCHER, ON STEPHANOSPHERA PLUVIALIS. 191 
Cienskowski, although I am not aware that the observations 
of the latter have been confirmed by any other observer. 
In case observers should in future meet with vegetable cells 
showing Ameeba-like structures within, special attention 
should therefore be paid to this point, as to whether they are 
foreign intruding parasites, or are really due to any phase or 
change of condition of the protoplasm of the vegetable cell 
itself. There cannot be a question, however, as to the accu- 
racy of Dr. Hicks’ and Professor Schenk’s observations, and 
that a parasite had nothing to do with the phenomena they 
describe. And that the primordial cells themselves of 
Stephanosphera actually became temporarily changed, as I 
have described, and not that they each became the choice 
morsel of aturglarious Amceba is, likewise, beyond the faintest 
shadow of a doubt. 
But, leaving out of view the Myxogastres, as well as any 
such cases possibly, but only conjecturally, similar to the 
authenticated instances here cited, I fancy it would not be 
difficult to find further examples, far less pronounced and far 
less striking, it is true, than in Stephanospheera, Volvox, 
Moss, or Rhizidium, of that automatic contractility which in 
these established cases makes itself so remarkable, as even to 
present phenomena characteristic of a true Rhizopod. 
Let us take a look, for instance, at the figures of the zoo- 
spore of Gidogonium at the moment of its escape from the 
parent-cell.* The contents of a cell destined to become a 
zoospore become withdrawn from the cell-wall, and somewhat 
contracted into a subelliptic figure; at one side there makes 
itself apparent a pale space, which is the place whence 
afterwards is to originate a crown of cilia. The parent- 
cell-wall splits, and the zoospore makes its egress, often 
through a space actually too small to allow it to pass without 
a modification of its form; and this, in such instances, is 
really what takes place. It may be said that its motions are 
assisted by the cilia; but they have not yet begun to play, 
nor, if they had, could they cause that alteration of figure, 
“like that of a Euglena, from second to second,” of which 
Cohn speaks.t There can, I think, be no doubt but that the 
zoospore here, in such accidentally difficult cases, is mainly 
assisted in its birth by its own innate contractility. Niageli,t 
*® See the following, e.g.:—Cohn, ‘Untersuchungen tiber die micro- 
skopischen Algen und Pilze,’ t. xx, figs. 1, 2, 22, 23; Pringsheim’s ‘ Jahr- 
biicher fiir wissenschaftliche Botanik,’ Band i, 1857, t. i, figs. 13, 14, 15; 
Vaupell, ‘Iagttagelser over Befrugtningen hos en Art af Slegten 
Oedogonium,’ figs. 4, 11, 12. 
+ Loc. cit. (‘ Untersuchungen iiker d. mikr. Alg. u. Pilze’), p. 231. 
+ © Pflanzenphysiologische Untersuchungen.’ 
VOL. V.—NEW SER. ) 
