XU
INTRODUCTION,
endochrome not thus transformed into gonidia lying beyond
them, and extending to the ends of the segments, by this time
OSes Its normal character, and seems to become drawn into detached
bands or strings, with a few free granules, and the
eimmal cavity, with the active particles, becomes lost. The
gonidia lately formed at the middle of the frond have now
emerged through the opened apex of the lateral tube, and
lemam clustered together in a mass very much like a bunch of
grapes, the clusters becoming by degrees larger and
arger, until all the gonidia make their exit through
the tube, and each adds its quota to the group The
same is the case when there are two or three tubes, the only
di&rence being that a fewer number, but generally about equal,
make their way through each. Meantime the unused eL o -
chiome, which had become drawn into detached strings, now
hses Its bright green colour, changing somewhat to an olive
finally turning brown, and quite dying, and even, to a great
extent, disappears. Each of the gonidia forming the external
cluster appears by this time to have formed for itself a special
cell wall of slightly compressed or elliptic form, within which
e green contents may often be seen somewhat retracted Now
a movement within its circumscribed prison may be seen on the
part of the contents of a few of the gonidia, which takes the
appearance of a twisting motion, backwards and forwards as it
were, on its axis, similar to what may be sometimes seen in the
organisms called Traolielomonas, by Elirenberg. I have not
noticed them to turn completely round. These gonidia are
however, greatly smaller, nor could I perceive any red spot If
such a comparison might not appear wholly out of place I
would be mduoed to say that the movement of the green contents
withm the confining membrane reminded me somewhat of
the movement of the eye in certain Entomostraca. This move
ment is not apparent in all the whole group of gonidia simultaneously,
but only in a few at a time. Eventually, one by one
the green contents leave the confining membrane in which they
have hitherto been detained, but I am unable to say in what
manner they made their exit. There certainly appeared no neck-
hke opening or perceptible aperture, but they probably escaped
by lupturing the boundary wall. Having, however, made their
In t r o d u c t io n .
escape, they swim away as ovate or pyriform ciliated bodies, pale
at the narrower or pointed end, and green otherwise through-
ont—in point of fact, veritable motile gonidia or zoospores, in
every way comparable to the similar bodies found in other
algie their principal distinction from those, for instance, in
Cladophora being their temporarily abiding in a cluster, each
encysted in its special coating. I vainly tried to satisfy myself
whether these zoospores were one or too-ciliated, but I was not
able to decide this difficult point. They were about '00027 inch
(•0068 mm.) in their narrower diameter, and somewhat greater
longitudinally.
Having one by one escaped, the vacated cells remain not long
attached at the apex of the lateral tube, and I think they fall
away therefrom sometimes in a more or less connected condition
and finally decay. The old frond now generally separates at the
suture, one segment bearing away the empty special structure
described, the other, of course, unchanged ; any remaining
endochrome by this time being quite brown, broken up and
dead, if indeed it be not altogether vanished. I imagine it might
be possible that in the native pool the whole endochrome might
be used up in the production of the zoospores. The empty cell
membranes or old segments were to be found for some time
afterwards in the gathering when all traces of the zoospores had
completely disappeared, and I may add that the formation of
zoospores occupied only two days, when there was a complete
cessation of their development. The gathering was made in the
month of September.”
Little remains to be said of the habitats, collection, and preservation
of these minute organisms. Being, for the greater
part, free swimming plants, they need not be sought in swift
streams, but rather in pools, ponds, little depressions in swampy
land, amongst Sphagnum in bogs, and in a few instances on rocks
subject to the continual drip of water. I t must be remembered
that they are confined to fresh and clear water, the rarest and
most interesting being found at a considerable elevation in
mountainous districts. Microscopists are now so efficient in
modes and appliances for collecting that it is unnecessary to
attempt details beyond suggesting that shallow and not deep
waters must be sought. Mounting for preservation is not in so