ARCHER, ON STEPHANOSPHERA PLUVIALIS. 119 
enegy of the gyrations of Stephanosphiera, the remarkable 
figure of the primordial cells, the differing sizes and curious 
appearances of the variously developed globes, might cause 
some to give the latter the preference as a handsome object. 
Hach, indeed, is certainly a charming sight ! 
To revert, however, to our subject. Notwithstanding that 
the structure and development of this organism has been 
copiously detailed in Cohn’s cited elaborate memoirs, a brief 
résumé here will be necessary in order to draw particular 
attention by and by to one or two points in its structure and 
organization, which I am disposed to think in some measure 
foreshadow the remarkable phase presently to be adverted to, 
Stephanospheera, then, consists, as we have seen, of a family 
or colony of eight green, biciliated protoplasm-masses (pri- 
mordial cells), destitute of a proper cell-membrane, and 
arranged in a circle, more or less approximately and at even 
distances from one another, at the equator of a common 
enveloping, hyaline, rigid membranous sphere, composed of 
cellulose—the “‘ envelope-cell” (“ Hiillzelle,’” Cohn). Though 
the normal form of the envelope-cell is spherical, I have 
occasionally, but extremely rarely, noticed such as possess, 
even when fully grown, an elliptic, or ovate, or subtriangular, 
or sometimes even a figure-of-8 shape; such very rare and 
casual distortions do not seem at all to interfere with the 
otherwise normal growth and movements. 
Itis by the action in the surrounding water of the two 
flagelliform cilia belonging to each primordial cell, protruded 
directly through the envelope-cell, that the revolving and 
onward movement of the total organism is effected. The 
primordial cells present great variety of form—in the sim- 
plest condition globular, or nearly so. But in a fully grown 
Stephanosphera, when viewed equatorially, these primordial 
cells very frequently appear to be elongated in a direction 
toward the poles, and very often to a greater extent in one 
hemisphere than in the other—reaching sometimes almost to 
the pole in one, and leaving the other partially empty—that is, 
an equatorial line in such cases would not cut the primordial 
cells into equal halves. These, whose general form in this 
condition in an old family, when viewed equatorially, may be 
said to be usually broadly fusiform or subelliptic, frequently 
present several filiform, often dichotomously ramified, more 
or less attenuated, colourless prolongations of the protoplasm, 
especially from their opposite ends, sometimes even tuft-like ; 
these are occasionally very divergent laterally, or even project 
towards the centre of the envelope-cell. When the organism 
is quite mature these colourless prolongations are mostly 
