124 ARCHER, ON STEPHANOSPHARA PLUVIALIS. 
“ macrogonidia ;” that is, the division of the primordial cells 
into two, into four, into eight, but not stopping here, but 
again dividing into sixteen, and so on, and finally into an in- 
numerable number of minute, elongate, fusiform, quadriciliate 
cellules—the “ microgonidia.” These do not at any stage 
secrete an envelope-cell, but remain crowded together within 
the original envelope-cell, inside of which they actively move 
hither and thither in an amazingly rapid and energetic way, 
than which there is scarcely any more astonishing sight ; 
these finally escape from the old seh Sbes cell by its rupture ; ; 
and losing their cilia, coming to rest, and assuming a reddish 
colour, become developed by a series of self-divisions and 
formation of special walls into structures somewhat like in 
form (and I believe in that only) to Botryocystis, or to 
Kiitzing’s Microcystis or Polycystis; of these any further 
development is unknown. It has been supposed that these 
microgonidia, as in Volvox, may be, perhaps, looked upon as 
spermatozoids; but no such function seems to be confirmed 
by actual observation. It is, perhaps, more probable that 
they are homologous rather with the microgonidia of Hydro- 
dictyon, a plant otherwise presenting so very many affinities 
with Stephanosphera. Pringsheim has shown that in 
Hydrodictyon the microgonidia are really structures intended 
themselves eventually to reproduce the plant in a future 
eason.* 
Tt will be seen that Stephanospheera differs from its well- 
established fellow-genera in Volvocinaceze—not to descend 
to minor but important details of structure and development 
—from Volvox, in having the zoospores or primordial cells 
eight only, and at the equator, not numerous all over the 
periphery of a sphere; from Pandorina, in having eight only 
at the equator, not sixteen or thirty-two, arra need i in tiers ; 
from Gonium, in having the eight primordial cells within a 
common spherical envelope, not sixteen, each having a thick 
coat, cohering by certain points of their surface into a tablet ; 
and from Protocoecus (Chlamydococcus), by the cells not 
being solitary. 
Having thus endeavoured to convey an idea of the nature 
and ‘appearance, of the structure and development of 
Stephanospheera, a necessary preliminary to the short and 
very imperfect note I have to offer, I now proceed to draw 
attention to the peculiar condition which it is meant to record. 
I have mentioned that, at a certain time, the primordial 
* € Berichte der Akademie der Wissenschaften zu Berlin,’ 1860; ‘Ann. 
des Sciences Natureiles,’ ivme Ser., t. xiv, p. 52; ‘Quart. Journ. of Mie. 
Sci NS. Vol, 1p. 54: 
