PROGRESS OF MICROSCOPICAL SCIENCE. 211 
was suspected years ago by Mr. Busk, but it is now clearly defined. 
Mr. Gilburt says that he lately obtained some water from a pond in 
Epping Forest, near Walthamstow, containing Volvox globator in great 
numbers. On first looking at them, nothing particular was observed, 
save that many were decaying, and were occupied by one or more 
rotifers and their eggs. Making a more careful examination, he found 
that in some of the vigorous and more active ones, a difference between 
the macro-gonidia existed—some of them being smaller in size, lighter 
in colour, and the disposition of their gonidia less regular. Using a 
higher power, the difference became more marked, and under a power of 
350 diameters those which departed from the supposed normal character 
appeared as the author has represented them in the drawing which 
accompanies the paper, a sphere as an ordinary Volvowx, but that some 
of the gonidia were missing, and their places occupied by compound 
bodies, in this and every other respect agreeing with the figures of 
Spherosira as given both by Ehrenberg and Busk. Submitting them 
to pressure so as to rnpture the cell-wall, he found that the compound 
bodies referred to escaped; and then appeared discoid in form, and 
composed of about thirty cells, flask-shaped, having a nucleus, being 
attached to each other by the smaller end, and furnished with abundant 
vibratile cilia, which can be seen in both aspects as figured. The 
action of the cilia imparts a slow, revolving, wheel-like motion to the 
group, but with very little progression. This motion can sometimes 
be seen while they are still within the containing sphere. In a single 
Spherosira as many as fifty-five of these compound bodies have been 
found. One most remarkable feature is, that while the Volvow globator 
may contain from two to seven macro-gonidia, yet in only two instances 
has he found more than one Spherosiva among them; though a very 
large number have been examined for this special purpose. 
The Formation of Spores in Lichens and Fungi.—A valuable essay 
on this subject has been translated from the French of M. Strasburger 
into ‘Grevillea’ for March. We can only abstract a few of the 
observations, more especially with reference to Physica ciliaris. The 
author says with regard to this species his own special researches 
show that the primitive nucleus really exists, and is found in the 
upper portion of the claviform ascus before the production of the 
spores. The ascus is filled with a protoplasm nearly uniform in 
density, and possesses a thick and very turgescent wall. The nucleus 
is spherical, especially dense and refractive in its upper part, as the 
examination of preparations preserved in alcohol demonstrates. The 
ascus augments in volume, the primitive nucleus disappears, and eight 
spores simultaneously arise in the superior part of the ascus. These 
spores approach each other closely, and absorb for their formation 
nearly all the superior protoplasm of the ascus. The spores appear 
complete. In the centre of each of them we observe a denser, although 
badly circumscribed spot. The young spores are at first solid, and 
surround themselves very rapidly with a colourless membrane of 
cellulose, which quickly increases in thickness. At the same time 
they increase in size, and their protoplasmic contents retire towards 
their walls. The denser, and at first central portion, which is an 
