CURREY, ON FRESH-WATER ALG. 209 
contents of the cell as had not been absorbed in the forma- 
tion of the secondary cells. 
There is, however, another mode of self-division where the 
spore, or resting cell, divides first into two and then into four 
segments, each segment being the counterpart of the original, 
which thus produces a new generation of resting cells. This 
latter mode of division has been supposed to take place 
in the red resting cells of Chlamydococcus; but it has 
been recently stated by Professors Cohn and Wichura that 
this case requires further proof. I am enabled to furnish 
some evidence on the point, for I have distinctly observed 
the process of self-division in some red resting-cells, which 
were probably those of Chlamydococcus. I say prodably, 
because the red resting-cells of Chlamydococcus are quite un- 
distinguishable from those of another of the Volvocinez, viz., 
Stephanosphera pluvialis, so that without following out the 
development it is impossible to predicate whether such red 
cells belong to the one or the otlier. 
Pl. IX, fig. 2 shows an instance in which one of these cells 
has become divided into two parts; and Fig. 3, an instance in 
which the self-division has gone further, andthe original cell 
has become separated into four secondary cells, each precisely 
similar to the primary one. 
In a recent paper by Cohn and Wichura, published in the 
Transactions of the Bonn Academy, and an abstract of which 
appeared in the last number of this Journal, a question of 
some physiological interest has been raised with regard to 
the nature of these red resting cells. They observed that 
these cells in Slephanosphera pluvialis, which are at first of 
‘a green colour, and furnished with cilia, increase in growth 
after the green colour and the cilia have disappeared, #. e., 
after they have assumed a state of rest, a fact which they 
consider to militate against their character as spores. 
“We have seen,” they say, “ that these resting cells, after 
they have been formed by the metamorphosis of a motile 
primordial cell, increase in growth considerably ; that they 
go through a further vegetative development, and have, 
therefore, not reached the termination of their vital process.” 
And they then add: “It is contrary to the idea of a spore, 
that it should continue to grow after having assumed the 
character of a resting cell, and the fact has never yet been 
observed in any single case.” It would seem that these re- 
marks are intended to be limited to the Alge; but it is 
worthy of observation, that the spores of the ascigerous Fungi 
frequently increase in growth, after escaping from the asci, 
and if this circumstance is not to be looked upon as affect- 
VOL. VI. R 
