are either quite obtuse at the free apex or strongly acuminated.
They appear to be bound together by a very pellucid
jelly, which is sometimes very visible, especially at the junction
of the alternate cells. The corpuscles have a pellucid border,
and a few globose bodies, by no means constantly three, immersed
in a green grumous mass. This at length entirely
vanishes, and the cells are left empty and colourless.
A portion of the terrestrial form of Vaucheria ccespitosa
having been placed in a vessel of water and exposed to the
rays of the sun, in a few days the sides of the vessel were
covered with a green stratum, which is the subject of the present
illustration. The genus Scenedesmus belongs to a highly
curious group of Algae, the free Desmidiacece of Kiitzing,
whose nature and limits are at present but little known. It is
probable that many of the species figured by Kiitzing, Meyen
and Turpin will hereafter be united. Amongst the true
S. obliquus many individuals occurred which might be referred
to described species, but I could not but consider them as different
stages of one species. Some of these are represented.
a, portion of plant, natural size; b, c, d, plant variously
magnified; e, corpuscles highly magnified; f , forms resembling
S. minor, acutus, quadrialternus, &c.—M. J. B.